Resembles a computer connector - huge with a series of pins at one end
Resembles a USB port - slides in like a plug into the slot of the source device
In DVI, the pixels are transmitted as binary data, and the brightness is set accordingly. The signals for DVI and HDMI are compatible with each other, hence, no signal conversion is required when using a DVI adapter for HDMI, and vice versa, which is why there is no loss of data.
Verdict! It is hard to choose a preferred option between HDMI or DVI, since both have their own advantages and disadvantages. While both pretty much perform the same job, HDMI, although more expensive than DVI, is preferred more by consumers, as it provides better quality, has better HD support, and more importantly, supports audio transmission as well on the same setup. Make your choice accordingly, and enjoy your favorite video in High Quality.