What’s the difference between BrowserAnimationsModule and NoopAnimationsModule?

What’s the difference between BrowserAnimationsModule and NoopAnimationsModule?

As the name noop (“no operation”) says, that module doesn’t do anything. It is a utility module that mocks the real animation module but doesn’t actually animate.
This can be handy on platforms where animation would be too slow, or for unit testing if the animation isn’t involved in what you actually want to test.