Hi
@JustinM88 -
I think you've got the basic idea, but I'd phrase it a little bit differently -- a slight adjustment would be that the opponent process theory has to do with
internal stimuli like pain/pleasure, whereas extrinsic motivation theory has to do with
external things. The issue with phrasing it in terms of "physical" rewards is that pain and pleasure have a physical basis, especially in the context of addictive behavior, so I think it's clearer to think of it as an internal/external opposition.
Hope this helps & best of luck!