Unfortunately, words used for colors can vary, especially since Nike et. al. make things up for marketing purposes. The only things you can trust are Pantone and other numbers. And the further back you go, the more you have to just estimate.
If college athletes are allowed to unionize (as they may soon), here's how I think we rank them:
1. NFL
2. College football
3. NBA
4. College basketball
5. MLB
6. NASCAR
7. NHL
8. MLS.
Definitions mean everything. If by "major league" you mean paid athletes (to some degree), big TV contract, nationwide spread, big numbers, big events ... I'd wanna throw college football in there. Before even MLS.