I just recently got into dance improvisation.  It's a whole new world for me.  I understand you know a thing or two about it? 
Improvisation is a free way to express yourself through dance. Artists like Michael Jackson are the epitome of dance improvisers and they love creating new forms of dance/expression. 
It makes sense MJ was a dance improviser.  He was so unique!  How can you tell the difference between normal dance performers and improv dancers?
Improv dancers always try to be unique each time they dance, so you won't see a lot of repetition. But normal performers follow rituals and strict choreography that they practice over and over.