But your example re: Dick and Bruce is a product of their differing personalities, and the interplay between the characters. When they were in costume, fighting the Joker, Two Face, et al I'd argue the differences weren't so pronounced. It was still a little bit of detective work, swinging round buildings, and a lot of punching people.
With GL it's ring slinging, aliens, Guardians, etc. With Flash it's running fast, the Rogues, and often clever wibbly wobbly timey wimey science fiction. Doesn't matter which GL or Flash is in the suit.
Okay. I might be over simplifying a little bit for effect. A little bit.
Bucky Captain America stories, however, feel different than Steve Rogers stories. Bucky's a lot darker, more shades of grey, espionage thriller; Steve's more black & white straight up superheroic.
When Brubaker tried to fit Steve into a Bucky type story, I'd posit that it didn't really work. That's why the Winter Soldier run is fondly remembered today, but the concurrent Captain America series is something of a footnote to Ed's run.