Terminology· 2 min
Open weights vs open source
Open weights = you can download the model file. Open source = you also get training data, code and a permissive license.
Key idea
Most 'open' models today (Llama, Mistral, DeepSeek) release weights under a custom license — not classical open-source.
Example
Llama 3 is open weights with a community license. OLMo from AI2 is closer to fully open source (data + code + weights).
What to remember
- Open weights enable local, private and fine-tuned deployments
- Licenses matter — some restrict commercial use or scale
- True open source is rare but growing (OLMo, Pythia, StarCoder)