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. 
Fascinating!  Do Improv dancers have any techniques to guide their performance since they don't rely on strict choreography?
Yes they often use feelings, mood, and emotion to guide them to certain movements and techniques. 
Gotcha!  What are some examples of other famous improv dancers?    
Steve Paxton founded Contact Improvisation,[2] a form of dance that utilizes the physical laws of friction, momentum, gravity, and inertia to explore the relationship between dancers.
Never heard of him before.  What else is he known for?  Has he invented a dance style or particular famous for a certain music genre dance performance?
friction, momentum, gravity, and inertia to explore the relationship between dancers.
Paxton believed that even an untrained dancer could contribute to the dance form, and so began his great interest in pedestrian movement. After working with Cunningham and developing chance choreography, defined as any movement being his generation whose approach has influenced choreography globally. He attempts to remain reclusive, except when performing, teaching and choreographing internationally.
Contact Improvisation.
Paxton was influenced by the experimental arts and performance scene in New York in the 1960s and
not only about creating "new" movement but is also defined as freeing the body from habitual movement patterns (see Postmodern dance and Judson Dance Theater). Dancer and singer Michael Jackson combined improvisation in both of those definitions, insisting that he had interest in performing a dance to "Billie Jean" only if he could do it a new way each time.
A lot of improvisation is focused on finding a deeper way of comprehending otherwise concealed thoughts or feelings of an individual. Through the emphasis of instinctual, unpredictable,