Trailers are an interesting subject. You can compare similar Ford, GM, and Ram trucks and the basic builds are much more similar than different. With trailers, you can put two side-by-side, with the same spec’d capabilities and they may be completely different. Beyond the main frame: channel, I-beam, tube, even angle; the box design and supports can all be completely different. Supports 12” on center are generally an upgrade (or on the premium lines), but I’ve seen trailers with 24” on center supports, with 16”-18” being the most common. Ironically, the one with the extra supports actually has a lower payload capacity, since it all comes from the GVWR.