I’m sure Nat 550cc are high profile anyway as you have told your surgeon wot look u wantThe high profile one will be somewhat narrower from side to side, but rounder. It will give you more fullness and roundness in the upper part of the breast, but possibly less cleavage/ more of a gap. It will tend to look more like “the push up bra” look than the medium profile
The medium profile implant will tend to be a little wider, but give less fullness on the top. In our practice, this shape is a little more popular, but it’s really a matter of patient preference. Both can look nice, when they are proportional to your frame, and placed by a skilled surgeon.