There's a huge gap. Just like there's a huge gap between, for example, bullets fired by a Webley and bullets fired by an M4. Even 'bullet-timers' are not all created equal, based on feats and at least some nod to the weapon used.
As for moving 'just under the speed of sound', if they're not just using that for travelling long distances through open environments, sure, they should have equivalent reaction speed. Someone who flies that fast, for example, might NOT unless we see them demonstrating that reaction speed in flight (flight through a building, zipping through the hallways, taking turns, avoiding people, etc). But someone who needs to 'run' at that speed? Yeah, they'd absolutely always need the reaction speed as well.