Llama 5 vs Llama 4: What Changed in Meta's New Model
Llama 5 vs Llama 4: What Actually Changed
Meta released Llama 5 on April 8, 2026, replacing Llama 4 as the flagship open-weight model. Here’s every meaningful difference.
Last verified: April 10, 2026
Quick Comparison
| Feature | Llama 4 | Llama 5 |
|---|---|---|
| Released | 2025 | April 8, 2026 |
| Flagship size | 405B dense | 600B+ MoE |
| Architecture | Dense | Mixture-of-Experts |
| Context window | 256K tokens | 5M tokens |
| Training compute | H100 cluster | 500K+ Blackwell B200 |
| Modalities | Text, image | Text, image, video, audio |
| Native agents | Partial | Full |
| Recursive self-improvement | ❌ No | ✅ Yes |
| SWE-bench Verified | ~62% | ~74% |
| MMLU-Pro | ~80% | ~87% |
| License | Llama Community License | Llama Community License (updated) |
Architecture Changes
Llama 4: Dense
Llama 4 used a dense transformer — every parameter activates for every token. 405B parameters meant 405B active every forward pass. Simple to serve, but expensive at scale.
Llama 5: Mixture-of-Experts (MoE)
Llama 5’s flagship has 600B+ total parameters, but only a fraction (likely ~40-80B, similar to DeepSeek V4’s design) activate per token. This makes inference 3-5x cheaper while allowing a much larger total parameter count.
Why it matters: You get more capability for the same inference cost, but serving MoE is more complex (needs expert routing, load balancing).
Context Window: 256K → 5M
Llama 4 capped at 256K tokens (enough for long documents, not for whole codebases). Llama 5 jumps to 5 million tokens — the longest of any frontier model in April 2026.
Practical implications:
- Ingest an entire medium-sized repository in one prompt
- Process book-length documents without chunking
- Long-horizon agent trajectories without memory compression
Recursive Self-Improvement (New)
Llama 5 introduces the ability to refine its own internal logic and generate high-quality synthetic training data. Meta describes this as moving toward “System 2 thinking” — slow, deliberate reasoning.
Llama 4 had no equivalent. This is the biggest architectural innovation of Llama 5 and the main reason Meta claims it matches closed frontier models on hard reasoning benchmarks.
Native Agentic Training
Llama 4 could be fine-tuned for agent workflows, but agentic behavior wasn’t baked in. Llama 5 is trained from the start on tool use, planning, and multi-step execution. You get:
- Better out-of-the-box function calling
- Stronger multi-step planning without prompt scaffolding
- Improved resistance to agent failure modes (loops, hallucinated tool calls)
Multimodal: Text+Image → Text+Image+Video+Audio
Llama 4 handled text and images. Llama 5 adds native video and audio input, matching GPT-5.4 and Gemini 3.1 Pro.
Benchmark Deltas
| Benchmark | Llama 4 | Llama 5 | Delta |
|---|---|---|---|
| MMLU-Pro | ~80% | ~87% | +7 pts |
| SWE-bench Verified | ~62% | ~74% | +12 pts |
| AIME 2025 | ~70% | ~88% | +18 pts |
| GPQA Diamond | ~72% | ~84% | +12 pts |
| HumanEval | ~89% | ~94% | +5 pts |
| LiveCodeBench | ~52% | ~68% | +16 pts |
These are the largest generation-over-generation gains in Llama history — bigger than the Llama 3 → Llama 4 jump.
License Changes
Both use the Llama Community License, but Llama 5 updates a few terms:
- Attribution: Still required (“Built with Llama”)
- MAU cap: Still 700M for the separate-agreement trigger
- Training other models: Llama 5 explicitly allows using outputs to train other models (Llama 4 was ambiguous)
- Multimodal outputs: Covered under the same terms
Migration Notes
- Tokenizer: Updated for Llama 5 — don’t mix Llama 4 and Llama 5 tokenizers
- Chat template: Minor formatting changes; update your prompt wrappers
- Fine-tunes: Llama 4 LoRAs and full fine-tunes do NOT transfer to Llama 5
- Tool use format: Llama 5 uses a cleaner JSON-based tool schema
- API clients: Hosted provider APIs (Together, Fireworks, Groq) accept a drop-in model name change
Should You Upgrade?
✅ Upgrade if:
- You have hardware to run Llama 5 (even the 70B distilled variant)
- You need longer context or better reasoning
- You’re building agents
- You want multimodal
⚠️ Stay on Llama 4 if:
- Your hardware can’t handle Llama 5
- You have production fine-tunes you can’t easily retrain
- Your workload is simple enough that Llama 4 is “good enough”
For most teams, upgrade. The benchmark gains alone justify the migration effort.
Last verified: April 10, 2026