In freestyle races, maybe. In races for specific strokes, there must be rules defining how you get across, otherwise there's no distinction between them.
You could liken it to the difference between running and walking races. Without the rules, a walking racer could discover an amazing new technique that greatly increases their speed - i.e. running. Or long jump vs. triple jump. Both are 'how far can you get across the sand without disturbing it'. you could get amazing triple jump distances if you could just keep running to the edge of the pit, then jump.
Even so, you could describe the point as who could get across the surface of the pool under their own power, and that there is a permitted amount of underwater time or distance due to the nature of turns and dives. Much like in a walking race, you can 'run' a limited number of steps, otherwise half the field would likely be disqualified in most races.
Butterfly was originally a breaststroke variant, as it complied with the then rules for that stroke. The rules for breaststroke were changed and a new event came about. Conversely, English Backstroke has simply vanished in favour of back crawl.