One big difference already alluded to other than the money is that as an RAF officer, you are an officer first and an ATCO second. This means all the other things that are required as well as controlling aircraft. If all you want to do is control aircraft, then go civil. If you want to control and be an officer, lead and go to places where people might shoot at you, join the Air Force.
I have done both - I have never regretted joining the Air Force but I was ready to leave and did so.
