"Spin" and "rotate" can be used to describe machines, or machine-like motion. A shaft in a motor will spin or rotate. A person hanging from a rope might spin or rotate. If the motion is slow, it is best to use "rotate"; spin is not slow. "Whirl" is less machine-like, and perhaps more complex motion than a simple rotation. A dancer might whirl. "Swirl" is even more complex motion, suggesting that there are parts of the motion going backwards and forwards. The long gown of a dancer might swirl about as the dancer is moving. "Twirl" is less serious motion. An acrobat or juggler might twirl a baton or other object for entertainment.