There are some places which are offering integrated CT programs, but those are categorical. Trauma is a fellowship after general surgery (CT usually is, too).
For the moment, focus on prelim surgery vs. categorical surgery. A categorical surgery match means that the program commits to you for 5 years (academic programs add 2 additional lab years). As long as you perform at some basic level of competency and don't quit, you are going to a board eligable surgeon at the end of that program. A prelim surgery spot is a single year commitment by the program, at which point you have to figure out what to do next -- options include staying at the same program for a second prelim year (again, no commitment from the program for beyond that year), transitioning to a categorical spot at the same program or at a different program (the program makes a commitment to you for the duration of your training; they may require you to repeat your intern year), switching to a categorical program in which one matches after the first year (for example, you can go into anesthesia). The important thing to realize is that you might be left hanging with no where to go after your preliminary surgery year -- it's possible none of those options open up to you.
Transitional years, like preliminary surgery years, don't come with a commitment beyond that one year. However, they tend to be a lot more cush, i.e., you rotate with a few months of surgery, a few months of medicine, some elective time, and so on. They're harder to get than prelim surgery. Usually the people who get them also had a match into something like anesthesia, where you have to do an internship in something before you start the anesthesia program.
Best,
Anka
