American suits have one vent in the back of the jacket (and if you
really want to get respect, call it a "
coat"), no shaping, and natural shoulders. Three buttons are the best, and available from
Brooks Brothers or
J. Press, most other, lesser tailors get by with two. English suits have two vents in the back, and a little more shaping. Most top English tailors ply their trade in
Savile Row, and have an extraordinarily complex method of measuring that takes into consideration how you sit, stand, walk, habitual motions...and of course, one's
dressing side. Italian, or "
Continental" suits are as above, with
no vent in the back. Perhaps some other poster can explain German, and military tailoring; I have little to go by except that it fits close to the body.
Speaking as a clothing freak, there's nothing nicer than to undress a man wearing the full kit...