I will post a little photo-essay showing the differences in dimensions. It's difficult to photograph the differences, but far easier to "feel" the differences. The Flattop has a much smaller "feeling" gripframe, which makes the whole works seem more trim. The revolvers shown, a 4-5/8" Super Blackhawk with the white grips, and a 4-5/8" Flattop with the red grips. Remember, these short-barreled Supers have a Blackhawk gripframe, where the longer-barreled Supers have a dragoon gripframe, which would be even larger, in all dimensions.
Both muzzles were flush while photgraphing both revolvers...
Frame window is larger on the Super...
Notice the larger frame window on the Super, causes the rear sight to be slightly farther to the rear...
The gripframe is obviously more meaty on the Super...
The overall length is roughly 3/8" longer on the Super...
WAYNO.
edited to add...Since the photobucket fiasco, I'm trying to replace relevant photos via postimage...