I've always been fascinated by words, and by the fact that they can have so many meanings. When I say, "boot", I usually think of something that goes on my foot, or on my horse's leg. In the UK, "boot" is the trunk of a car. When we say, "trainers", we're often talking about our riding instructors; in the UK, "trainers" are sneakers. And (my favorite) when we talk about Curlies, we're often referring to Bashkir Curlies, a breed of horse (http://www.abcregistry.org/gallery08/pages/calendar-75.asp). In the UK, "curlies" is slang for pubic hair ... so you can imagine the uproar at Black Country Saddlery when we sent them a template for a woman who wanted to order a saddle for one of her Curlies ...
Anyway, another word (or phrase) with different meanings here and Across the Pond is "saddle fitter". In the UK, a saddle fitter is someone who helps you find a saddle that fits you and your horse. A saddler (or master saddler) would be the one to adjust the flocking, alter your billet configuration, and do similar work to adjust the fit of your saddle or do repairs.
Over here, "saddle fitter" is more of a broad term. In addition to finding the right saddle for horse and rider, we often do repairs, flocking adjustments, retrofit saddles ... just about anything. This is mostly because of the lack of standardized education here in the US; in the UK, the saddlery business is much older, larger and more structured. There are Master Saddlers, Allied Trade Members, Qualified Saddle Fitters, and more - you can read about all the different "Categories of Membership" at http://www.mastersaddlers.co.uk/.
I've always had mixed emotions about saddle fitters (whichever definition you're applying) who rep for a saddle company. As a saddle fitter, I think it's my responsibility to find the right saddle for you and your horse, whichever company happens to make it. Admittely, I have the luxury of working for a shop that has a relatively huge inventory of new and used saddles; we carry new saddles from about a dozen different companies - and often multiple models from each company - and our used inventory is massive. That gives me the opportunity to find the right saddle for each horse and rider without having to worry about making my sales quota or getting (or losing!) a commission. My situation is relatively rare.
For a fitter who's also a rep, it can be a very different story. On the one hand, I know some excellent fitters who are also reps, but will work on the fit of mostly any saddle, and be perfectly honest in their assessments of saddles and fit (and I have to say that these fitters are in the majority). But human nature being what it is (and economic reality and commissions being what they are), some fitters will try to sell you one of their saddles ... whether you need one or not. The main problem in that situation (ethics aside) is that there's no single saddle company, no matter how many models they make, that produce the perfect saddle for each and every horse and rider. Even the best saddle companies - the ones that offer multiple models with a bazillion fitting options for horse and rider - can't satisfy everyone. Having a choice (both for you and for the fitter) gives you a wider range of options, and increases the likelihood that you'll find the right saddle.