An RAE cannot be directly converted into an IU without knowing the source(s) of vitamin A. For example, the RDA of 900 mcg RAE for adolescent and adult men is equivalent to 3,000 IU if the food or supplement source is preformed vitamin A (retinol).
On the other hand, an Associate degree is a title conferred on a student when he completes a college study. Diploma is usually given in vocational or professional courses, like designing, pharmacy and engineering. High schools, trade colleges and professional schools confer Diploma certificates.
Again, it all depends on the college. Another difference is in the scope of study - a bachelor's degree tends to cover a broad range of topics under a certain field, whereas a master's degree concentrates on narrower subjects. The concepts taught in a master's degree are also more advanced than a bachelor's degree. The third difference lies in the earning potential of the two degrees.