I'm not sure how one can tell California dancers from New York City dancers. Are they wearing badges or can you tell from the tans?
If you've studied Jazz dance, it should be easy to differentiate between NYCity and California dancers. NY dancers' bodies flow with the music as their souls mesh with the musical beat. California dancers all look like they just made it through Jazz Dance 101 and are now on their way to level 102. Their bodies look "jerky", while in motion. Not a professional appearance fo sure.
Basically, I've noticed that the California dancers put most of their Jazz warmup routines into their dances. This makes them look, to me, less professional than the dancers from NY.