I believe one of the key differences is that fewer people shoot at the civvy one.
Could be wrong though . . . (all the guys on Safair no doubt are shouting - YOU ARE!)
Military ones are also painted more interesting colours:
RAF in mid 70's, two tone brown and black underneath - operating in Western Europe tactically.
Aha lets paint them grey and green - yes you guessed, now send them into the Gulf (again).
Operating in desert environment so let's paint them light blue or even dark green (all over). Logic appears to be, you've got to give the locals SOMETHING to aim at, like the 'shoot me here' white crosses in Ethiopia (bullet just missed LOX converter).
See what I mean? - Now you can see why there's no Government Surplus paint available anymore - it's all in Cambridge!