Jimmy, there are all kinds of parameters that a guy can play with, and most makers have their own set of ideals. Chamber depth, chamber width, and the overall shape of the chamber (cylindrical or conical), airway diameter, the joint between the stem and the shank, the airway in the stem, shape of the button, shape of the slot inside the button. All will radically change how a pipe functions.
Briar from different regions is said to taste different, and some makers treat their briar with oils (or oil removers) for some kind of special distinction.
Pipes do differ, and as long as the basic mechanics are done well, it will smoke well. However, personal technique may mean that some smokers prefer a smaller airway, or a wide bowl, or whatever.
I think there's tons of pipes out there that baring the shape of the bit in the mouth, smokers could not tell what pipe it was.
That said, I treat all my briar in a secret mystical gravy that was passed to me in a dream by the Great Omnipotent, uh, Eugene, God of all Pipey Wonderousness, and you should buy one right away because it will be totally better than anything you ever tried. :twisted: