Pretty much as Endeavour said, with one proviso: On extremely rare occasions, transportation between theme parks and hotels may be limited, for short periods of time, to hotel guests. That's happened to use only twice in about two dozen visits, and only happened at park-closing time, and only for a very short period of time, and only because the park was incredibly crowded, and so many people were trying to get back to their hotel at the same time.
You almost surely will not encounter such a restrictions, but it cannot hurt for you to know about the infinitessimal possibility.