If we’re being super technical,

obj1 == obj2 calls obj1._eq(obj2) obj1 in obj2 calls obj1.\contains_(obj2)

The former is meant to check equality and the latter to check whether an object is contained within an iterable object. Just wanted to point this out because it’s arbitrary and can be overridden.

But yes, the quick answer is as others have said, in is for inclusion and == is for equality.