A short term disability is a disability that will usually end within a few weeks or months. For example, if you are a gardener or a janitor and you break your arm, you will be unable to work for a month or two. You will have a short term disability.
A long term disability, on the other hand, is one that is expected to persist for a long time, and that may be permanent.
A pension is a permanent thing, and would only be awarded to someone whose disability was deemed to be not only long term, but permanent.
Student or Learner