Control augmentation (F-15, Su-27, F-5, etc) ALTERS your inputs slightly to allow for more predictable flying qualities.
Fly by wire REPLACES your inputs with control surface movements that generate the desired response. For example, at full back stick the mirage will deflect the elevons down a bit to keep the AoA below 30.
Press right ctrl + enter if you want to see what the FBW is doing to your inputs. It's pretty amazing to watch.