The hollywood principle is actually to me the definitive criteria. You plug your code into React and React ends up orchestrating and coordinating between your code, thus it is in charge of calling it and in what order etc.
That's normally what I would call a framework.
Now I don't know, maybe there's ways to use React only as a library, not sure if it would provide any benefit in that way.
> Lot of frameworks actually are a combination of two things:
> 1. the actual "way of building apps" > 2. useful library of functions
This describes React pretty much spot on. And yet, React people are very determined to point out that it's React is a library, not a framework.