However they are different aspects of the same verb I see them like having different meanings:
поступать = to apply to a center (university, f.e.), work, aso.
поступить = to access to the center, work, applied after a good evaluation of the application.
So: "Я поступал в институт, но я не поступил". I have seen this use in various exercises, but in dictionaries it is somewhat mixed.
What is your oppinion? Tks.