I am a non-expert when it comes to licensing but based on my read of the policy, it falls in between Open Source and Source Available, and calling it either without clarification would be somewhat misleading.
I think it is much more permissive than “source available” implies, because:
You are granted a non-exclusive, worldwide, non-transferable and royalty-free limited license under Meta’s intellectual property or other rights owned by Meta embodied in the Llama Materials to use, reproduce, distribute, copy, create derivative works of, and make modifications to the Llama Materials.
On its own the above is inline with FOSS principles, BUT it falls short of being fully free and open source because of these two caveats:
You will not use the Llama Materials or any output or results of the Llama Materials to improve any other large language model (excluding Llama 2 or derivative works thereof).
And because:
If, on the Llama 2 version release date, the monthly active users of the products or services made available by or for Licensee, or Licensee’s affiliates, is greater than 700 million monthly active users in the preceding calendar month, you must request a license from Meta, which Meta may grant to you in its sole discretion.
edit: for reference that means even companies as large as Twitter, Reddit, or Twitch, would not be subject to this clause.
So while it does fall short of fully open source, that sounds like it only applies if you are the owner of an app or service with greater than 700,000,000 monthly active users, or if you are trying to use Llama to improve a competing LLM that is not based on Llama. Basically it falls short of open source, but not in ways that are likely to impact anyone who is not (1) a multi-billion dollar tech comparny, or (2) using Llama to build an LLM from scratch. (or I’m a non-expert and I’ve misread things, and I should be corrected or ignored )