David W. answered 09/11/15
Tutor
New to Wyzant
A chair is what you sit on in class.
Old professors never die, they just lose their class.
Old deans never die, they just lose their faculties.
= = = = just a little humor. If you're in college, you'll need it.
A prof teaches classes and may also do research or work on projects (grants or contracts that bring money to the school). Think of them as "teachers." The others may also teach, because that's likely how they got to where they are now.
A chair is the head of a department (sometimes just elected by the other profs; sometimes appointed or hired into that position). It takes time and skill to get all the profs to work together (which is why you may meet grey-haired or bald or very forgetful profs who have become department chairs). At some schools, this is a great job; at others, nobody wants all the extra work (and, possibly, without extra pay).
The dean is the next higher level of management. The dean oversees a "school" or other unit of the college (like Dean of Admissions or Academic Dean) rather than departments.
They job of provost is different with each college. It is a senior academic or research position and may have considerable influence in what the college does.