The Samsung Galaxy S series of devices will all have a different design when they hit the US carriers. The AT&T version, the Captivate, has a very thin and wedge-shaped design. The back of the device is made from real metal, while the rest of the phone uses a mix of glass and plastic, giving the device an overall quality, but light-weight feel. The 4.0" WVGA Super AMOLED screen has an interesting blue shine to it.
For TV-Out, the Captivate uses microUSB, unlike the Droid X and EVO 4G which use HDMI. There's also a 3.5mm headphone jack. The microSD card is placed in a spot where you don't need to remove the battery to access it, which is a welcomed touch.