Daniel Vaughn is the BBQ Editor for Texas Monthly and the author of The Prophets of Smoked Meat: A Journey Through Texas BBQ. He explains the difference in the regional Texas barbecue below:
East Texas - This is closest to Southern BBQ often serving tender ribs covered in sauce, chopped beef sandwiches and hot links. In the East, sauce takes more of a prominent roll.
Central Texas - This is almost the opposite of East Texas BBQ. In general sauce is served on side. Vaughn says there is "no need for the sauce" in Central Texas where meat is smoked over indirect heat.
South Texas - Traditionally Southern Texas serves whole-head barbacoa cooked in underground pits. Vera's in Brownsville is the only place left that does this style of barbecue.
West Texas - West Texas is the Hill Country. Meat is cooked with direct heat over wood coals.