Photolinger wrote a good guide to the basics of most of the types of pipes available in the US. His guide goes over the basic countries of origin and some of the more known brands.(http://www.hookahpro.com/forum/showthread.php?t=11029
) The biggest differences to look for are in the construction. A lot of people like the large gauge downstems because the downstem makes for less restricted draw. Another thing to be aware of is the chamber. I prefer traditional chambers because they have a stronger purge. Common chambers do not purge as quickly or as thoroughly.