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Qwen3.5-397B-A17B vs Gemma 4 31B

How Qwen3.5-397B-A17B (Alibaba Qwen, February 2026) and Gemma 4 31B (Google DeepMind, April 2026) are built, drawn on the same November 2026 blueprint. They make different choices on 16 of 29 components. Select a component in either diagram to find it in the table.

--- frontier-llm@2026-11+++ qwen3-5@2026-02+0~3−3

Qwen3.5-397B-A17B

Alibaba Qwen, February 2026, 397B total, 17B active

Text · code · tool outputText · code · tool outputImages · video · audioImages · video · audioByte-level BPE tokenizer — 128K–262K vocabByte-level BPE tokenizer128K–262K vocabVision / audio encoder — native ViT or encoder-free patchesVision / audio encodernative ViT or encoder-free patchesToken embedding — media embeds spliced in placeToken embeddingmedia embeds spliced in placeEngram n-gram memory — hashed 2–4-gram lookup (V4.1)Engram n-gram memoryhashed 2–4-gram lookup (V4.1)Single residual stream — Residual & normSingle residual streamResidual & normRMSNorm — pre-normRMSNormpre-normQK-Norm — per-head RMSNorm on q, kQK-Normper-head RMSNorm on q, kPartial RoPE / NoPE — rotate 64 dims, or nonePartial RoPE / NoPErotate 64 dims, or noneGated DeltaNet / KDA — linear · ~3 of every 4 layersGated DeltaNet / KDAlinear · ~3 of every 4 layersGated grouped-query attention — AttentionGated grouped-query attentionAttentionSparse / compressed attn — DSA indexer · CSA / HCASparse / compressed attnDSA indexer · CSA / HCASliding-window attention — local · 128–1,024-token windowSliding-window attentionlocal · 128–1,024-token windowOutput gate + sink — σ(x·W_g) ⊙ o · learnable sinkOutput gate + sinkσ(x·W_g) ⊙ o · learnable sink⊕ residual⊕residualRMSNorm — pre-normRMSNormpre-normSoftmax top-k router — Mixture of expertsSoftmax top-k routerMixture of expertsRouted experts — top-6–22 of 256–896 · SwiGLURouted expertstop-6–22 of 256–896 · SwiGLUShared expert — 1–2 · always activeShared expert1–2 · always active⊕ residual⊕residualFinal RMSNormFinal RMSNormLM head — untied · vocab logitsLM headuntied · vocab logitsMTP module(s) — predict t+2 … t+kMTP module(s)predict t+2 … t+kNext-token logitsNext-token logitsDraft tokensDraft tokensMuon optimizer — Newton–Schulz · QK-Clip · per-headMuon optimizerNewton–Schulz · QK-Clip · per-headFP8 → FP4 training — block-scaled FP8 · MXFP4/NVFP4 QATFP8 → FP4 trainingblock-scaled FP8 · MXFP4/NVFP4 QATLong-context extension — staged 4K → 1M · YaRNLong-context extensionstaged 4K → 1M · YaRNRL with verifiable rewards — GRPO family · async agentic RLRL with verifiable rewardsGRPO family · async agentic RLOn-policy distillation — reverse KL to specialist teachersOn-policy distillationreverse KL to specialist teachersSpeculative decoding — MTP self-drafting · DSparkSpeculative decodingMTP self-drafting · DSparkKV-cache compression — FP4 KV · cross-layer reuse · SSDKV-cache compressionFP4 KV · cross-layer reuse · SSD
AttentionMixture of expertsResidual & normInput & outputTraining & inferenceData flowResidual / skipAddedReplacedNot usedNot disclosed

--- frontier-llm@2026-11+++ gemma-4@2026-04+2~7−6

Gemma 4 31B

Google DeepMind, April 2026, 30.7B

Text · code · tool outputText · code · tool outputImages · video · audioImages · video · audioSentencePiece BPE with byte fallback — Input & outputSentencePiece BPE with byte fallbackInput & outputVision / audio encoder — native ViT or encoder-free patchesVision / audio encodernative ViT or encoder-free patchesToken embedding — media embeds spliced in placeToken embeddingmedia embeds spliced in placeEngram n-gram memory — hashed 2–4-gram lookup (V4.1)Engram n-gram memoryhashed 2–4-gram lookup (V4.1)Single residual stream with per-layer scalars — Residual & normSingle residual stream with per-layer…Residual & normRMSNorm — pre-normRMSNormpre-normQK-Norm — per-head RMSNorm on q, kQK-Normper-head RMSNorm on q, kRoPE by layer type: full RoPE local, p-RoPE global — AttentionRoPE by layer type: full RoPE local, p…AttentionGated DeltaNet / KDA — linear · ~3 of every 4 layersGated DeltaNet / KDAlinear · ~3 of every 4 layersGlobal GQA with keys reused as values — AttentionGlobal GQA with keys reused…AttentionSparse / compressed attn — DSA indexer · CSA / HCASparse / compressed attnDSA indexer · CSA / HCASliding-window attention — local · 128–1,024-token windowSliding-window attentionlocal · 128–1,024-token windowOutput gate + sink — σ(x·W_g) ⊙ o · learnable sinkOutput gate + sinkσ(x·W_g) ⊙ o · learnable sinkPost-attention RMSNorm (sandwich norm) — Residual & normPost-attention RMSNorm (sandwich norm)Residual & norm⊕ residual⊕residualRMSNorm — pre-normRMSNormpre-normDense GeGLU feed-forward — Mixture of expertsDense GeGLU feed-forwardMixture of expertsPost-feed-forward RMSNorm (sandwich norm) — Residual & normPost-feed-forward RMSNorm (sandwich no…Residual & normRouted experts — top-6–22 of 256–896 · SwiGLURouted expertstop-6–22 of 256–896 · SwiGLUShared expert — 1–2 · always activeShared expert1–2 · always active⊕ residual⊕residualFinal RMSNormFinal RMSNormTied LM head with logit soft-capping — Input & outputTied LM head with logit soft-cappingInput & outputAutoregressive MTP drafter (4 layers, reads trunk KV) — Input & outputAutoregressive MTP drafter (4 layers,…Input & outputNext-token logitsNext-token logitsDraft tokensDraft tokensMuon optimizer — Newton–Schulz · QK-Clip · per-headMuon optimizerNewton–Schulz · QK-Clip · per-headFP8 → FP4 training — block-scaled FP8 · MXFP4/NVFP4 QATFP8 → FP4 trainingblock-scaled FP8 · MXFP4/NVFP4 QATLong-context extension — staged 4K → 1M · YaRNLong-context extensionstaged 4K → 1M · YaRNRL with verifiable rewards — GRPO family · async agentic RLRL with verifiable rewardsGRPO family · async agentic RLOn-policy distillation — reverse KL to specialist teachersOn-policy distillationreverse KL to specialist teachersSpeculative decoding — MTP self-drafting · DSparkSpeculative decodingMTP self-drafting · DSparkKV-cache compression — FP4 KV · cross-layer reuse · SSDKV-cache compressionFP4 KV · cross-layer reuse · SSD
AttentionMixture of expertsResidual & normInput & outputTraining & inferenceData flowResidual / skipAddedReplacedNot usedNot disclosed

Component by component

Qwen3.5-397B-A17B and Gemma 4 31B differ on 16 of 29 components.

Blueprint componentQwen3.5-397B-A17BGemma 4 31B

Same as the blueprintByte-level BPE (Qwen2Tokenizer): 248,044 BPE entries plus 33 special tokens, padded to 248,320 rows. The pre-tokenizer splits numbers into single digits. Qwen says the ~250K vocabulary (vs. ~150K in Qwen3) boosts encoding/decoding efficiency by 10–60% across most languages.

SentencePiece BPE with byte fallbackGemini's 262,144-entry SentencePiece vocabulary: character-level BPE, split digits, bytes only as a fallback.

Single residual streamOne d = 4,096 pre-norm residual stream with zero-centred RMSNorm gains; no hyper-connections or depth attention.

Single residual stream with per-layer scalarsOne d = 5,376 stream, RMSNorm before and after each sublayer, and a stored scalar that rescales the stream after every block.

Same as the blueprintPartial, interleaved multimodal RoPE (M-RoPE) in the attention layers only: 64 of 256 head dims rotate (partial_rotary_factor 0.25), θ = 10,000,000, with the 32 frequency pairs split 11/11/10 between time, height and width. The Gated DeltaNet layers carry no explicit position.

RoPE by layer type: full RoPE local, p-RoPE globalLocal layers rotate all 256 dims (θ = 10⁴); global layers keep only the 64 fastest of 256 frequency pairs (θ = 10⁶).

Same as the blueprintGated DeltaNet in 45 of 60 layers, three before every attention layer. 16 query/key heads and 64 value heads of dim 128 (each q/k head serves 4 value heads); short causal conv (kernel 4) + SiLU on q, k, v; per-head scalar decay g = −eᴬ·softplus(a + dt_bias) and write strength β = σ(b). Each layer keeps a 64 × 128 × 128 state per sequence, held in FP32.

Not used

Gated grouped-query attentionEvery fourth layer: full causal GQA with 32 query heads sharing 2 KV heads of dim 256, QK-Norm and a sigmoid output gate.

Global GQA with keys reused as valuesEvery sixth layer: full causal attention, 32 query heads and 4 KV heads of dim 512, V taken from the key projection.

Not used

Same as the blueprint50 of 60 layers, in runs of five between global layers. Each uses a 1,024-token window with 32 query heads and 16 KV heads of dim 256 (2 query heads per KV head), separate K and V projections and full RoPE with θ = 10,000. Their KV cache is bounded at 1,024 tokens per layer.

Same as the blueprintIn the attention layers q_proj emits 2 × 32 × 256 values per token; the second half is an elementwise sigmoid gate, computed from the layer input, applied to the attention output before W_o. Gated DeltaNet layers gate their output with SiLU(z) after a per-head RMSNorm. No sink logits.

Not used

Softmax top-k routerA linear router scores 512 experts; softmax, keep the top 10, renormalize. No selection bias.

Dense GeGLU feed-forwardOne gated MLP per layer, 5,376 → 21,504 → 5,376 with tanh-approximated GELU; all 30.7B parameters are active.

Same as the blueprint512 SwiGLU experts with intermediate size 1,024 at the full model width 4,096 (no latent projection); 10 are active per token, about 2% of the pool. Weights ship in BF16, with an official FP8 variant.

Not used

Same as the blueprintOne shared SwiGLU expert per layer (intermediate 1,024) runs on every token, but its output is scaled by a learned per-token sigmoid gate σ(w·x), w ∈ ℝ^4096, before it is added to the routed sum. Unlike DeepSeek-style shared experts it is not ungated.

Not used

Same as the blueprintUntied 4,096 → 248,320 output projection (~1.02B parameters), also used by the MTP layer; kept in BF16 in the FP8 release.

Tied LM head with logit soft-cappingLogits come from the input embedding matrix (no separate head) and are squashed by 30·tanh(z/30).

Same as the blueprintOne MTP layer: a full gated-attention + 512-expert MoE block whose input is a linear projection (8,192 → 4,096) of the RMSNorm'd next-token embedding concatenated with the RMSNorm'd trunk state. It reuses the main embedding and LM head and, per the model card, was trained with multiple steps, so the one layer is applied repeatedly to draft several tokens.

Autoregressive MTP drafter (4 layers, reads trunk KV)A separate ~500M-parameter, 4-layer Transformer drafts tokens one at a time while attending to the 31B's own KV cache.

Same as the blueprint262,144 tokens natively. The model card extends this to 1,010,000 tokens with static YaRN (factor 4 over 262,144) on the rotary dims, and warns that static YaRN can hurt performance on shorter texts. The pretraining context schedule is not published.

Not disclosed

Same as the blueprintQwen describes RL scaled across million-scale agent scaffolds and environments on an asynchronous, fully disaggregated training–inference framework, using FP8 end-to-end training, rollout router replay, speculative decoding and multi-turn rollout locking for throughput and train–inference consistency (3–5× end-to-end speedup). The policy-optimization algorithm is not published.

Not disclosed

Not present

Post-attention RMSNorm (sandwich norm)The attention output is RMS-normalized with a learned gain before the residual add; there is no output gate or sink.

Not present

Post-feed-forward RMSNorm (sandwich norm)The MLP output is RMS-normalized with a learned gain before it is added to the residual stream.

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