Downsizer.... a medical discharge forces you to leave the service on medical grounds, full stop. If, for example, you are aircrew and a downgrade in medical cat means that you can no longer fulfil aircrew duties then you may be offered service in another branch which has lower medical grading. However, should you be offered another branch but do not wish to fulfil it then you will be offered an admin discharge. (Or at least that was the case some 10 years ago when I had a med cat issue). In this case, the pension was the same as that for the medical discharge. I found the medical branch very fair and supportive during my medical recat at CME - they are open and honest with you and explain the options at every step of the way.