Special relativity says that there is no privileged perspective with respect to linear velocity, but general relativity showed that rotating reference frames are different, since one frame sees a centripetal forces while the other frames sees a centrifugal/gravitational force.

To put it differently, if I pass someone on the train moving at constant velocity, there's no experiment that I can perform which proves that I'm moving while the other person is standing still, or vice versa.

However, if I'm in a centrifuge, instead of on a train, then I can figure out which one of us is moving by measuring who is pressed up against the wall and making funny faces.