I don’t even know if “course” is the better word choice in the title of this question.
Those things may be obvious for Americans, but it’s tricky to understand the elements of the academic life in a given country because the words are similar or the same in other countries, but with different meanings. I searched those meanings, but it’s hard to understand them isolated and without examples (how they usually appear). I assume those things are too obvious to be explained (even by colleges themselves), but only learned in practice. If someone has a link to a college explaining the structure of what it teaches through a diagram I would be amazed.
If I want to become, for instance, a Nutritionist, I would get into a Nutrition ____ (program?/course?) in order to earn a Nutrition ____ (degree?). When people ask me what I do in college, I answer that I ____ (study? / am coursing?/ am majoring in?) Nutrition. In this semester I have a _____ (course?/subject?/either of both?) called Physiopathology of Nutrition II that is really hard. If I wanted to say that I want to give up Nutrition, I'd say "I want to give up this ____ (course?/major?/college?/degree?)."