I felt this was sufficiently important.
The progression of their hairstyles through the games!
Phoenix's hair, when he was in college, has spikes that are more rounded- His hairline is also softer compared to that of his older incarnations! At the beginning of the first game, he’s got a sharper look to his hair, though it’s flattened out a little bit.
In AA:DD, Phoenix’s hair gets much more tame (probably from years under that beanie!), but besides his new hair curl in the front, his hair gets a slightly softer look and his hairline is higher than it used to be.
As time passes, Edgeworth's bangs get progressively longer, and they also grow to be less angular. His hairline also gets to be less sharp: Bratworth has higher widow's peaks than his DD counterpart does.