Hi there,
Yes, there are differences in physical features for sure. Here's is a great link to a comparison pic:
https://2img.net/h/i188.photobucket.com/albums/z161/jeroenkooijman/exitialis%20article/P_sp.jpg
I actually like the look of P. exitialis more than P. imperator.
Here is a great link to their care and identification: http://www.venomlist.com/forums/index.php?showtopic=21777
The link also answers your questions pretty well too.