A leatherback is a leatherback. Pretty sure belgian/american is just a breeder term.
There was a thread about this awhile back and im 90% sure that was the response from Tom, a very well known and respected breeder on here.
(sorry to him if I am remembering wrong lol)
Your correct Bradon it is just like when "Belgian Translucent's" where a big thing a few years ago, it is a translucent just different genetic lines, usually imported lines.
The only big difference between types of leatherbacks is the one between the American and Italian leatherbacks. Americans are often called American smoothbacks. The genetics that create the smoother/leathery back are different. Italian leatherbacks have a co-dominant gene, which means that if you breed a regular dragon with a leatherback, you will get 50% leatherback scaled and 50% normal scaled. American smoothback/leatherbacks come from a recessive gene, so you need 2 dragons that have the gene to produce babies that are leatherback scaled. I read that some consider the American version to also be co-dominant but I think they are just renaming the genetics originally developed in Italy. Both look the same so if you're looking for a pet, either is fine. If you are going to breed though, ask about the genetics.