What "Is" Barbeque or "BBQ"? Possible Duplicate:
  What styles of barbeque exist in American cuisine?  




There are many different techniques, practices and (of course) sauces that are given the label "Barbeque" (or BBQ, or Bar-B-Q, or....). 

What are the various styles of BBQ, and what distinguishes them?

What (if anything) is/are the common threads that tie them all together?
You question has a short answer to it.

Barbeque - What you do on a gas or charcoal grill

BBQ - shredded, pulled or sliced pork, lamb or beef seasoned with a hot pepper and vinegar , mustard based, tomato based or mayo based sauce.

For more on BBQ the BBQ song - http://www.youtube.com/watch?v=6ubTQfr_tyY