http://www.squidoo.com/subwoofersbox
http://www.crutchfield.com/S-O2IoOzpUijY/popups/box_type.html
Its a good question.
Those sites can help answer.
Sealed boxes are usually the easiest to build because its less necessary to be 100% accurate on the inside area.
Ported boxes have some sort of port in them to allow sound out of the back of the woofer to escape and add to the overall volume.
Bandpass boxes are just to impress you in the stores. Unless you are entirely sure of what they are and how to tune them correctly i would stay away.
hope this helps.