Pretty close because the reference model is the Samsung Galaxy S, then all the US carriers are doing a tweaked version with it's own name/branding. So the AT&T phone is a Captivate, the T-Mob is a Vibrant, etc.

The AT&T version has pretty solid aesthetics: the front is edge-to-edge glass, and like the battery cover/rear is metal with this carbon imprinted grip surface.

The Galaxy S (line) uses a unique processor too - it's not the same as most of the other CPUs, most of the other 1GHz procs are Qualcomm Snapdragons, the Samsung has a really fast CPU called Hummingbird (like 3X the 3D performance, audio RABP). The Droid X is also using a specilized CPU (TI OLAP) that's supposed to have some faster integrated tech too.

I considered the Droid X, but I would've had to change carrier (and lose all sorts of bundled discounts), and it was a touch on the chunky side. The captivate is ~9.9mm without any bulges or anything.