Don't be surprised when salesmen don't know as much as you do. They only know what they're trained. People that follow the industry or research a product quite often know a lot more than the reps.
Saying the Droid X has a Snapdragon isn't the worst thing they could say...it's pretty similar to the TI OMAP3630...though I think the OMAP3630 is a little better because of its GPU.
I have no hard evidence. But from what I've read its kind of like the AMD Intel thing.
Where a "slower" AMD can run with a "Faster" Intel. So theoretically still being both rated at 1ghz the OMAP should still process faster.. Of course the separate GPU won't hurt.