Hi General

The Genesys has speakers and a small hard drive (I think it's 8 Gig)
The Genesys S and Pro do not have speakers and are a lot lighter. I believe the operating system is also newer

The Pro S has a 20 Gig hard.

The Genesys XP is a module version of the pro and I have one of those.

All of the units are very well built and are pretty reliable. I believe You will get a lot more info shortly from other memebers.

Jerry