@oristarA,
Staff and faculty means the same as staff and teachers. At college level, teachers come with various titles: Professor, Associate Professor, and who knows how many more. The don't like being called teachers, as teachers usually teach kindergarten and grades 1 -12. Of course, those titles apply to the US. Expect UK to be different. Of course, if you want one word to cover all, it is probably employees.
Leaders can probably be anyone. Staff is made up of what you might call the worker bees. That is, they carry out office, maintenance, janitorial functions, and so forth.
Was there an answer to your question in there, somewhere?