How does he have a better run speed or grab game? Their grabs are nearly identical and have similar applications. Except Falcon has better disjoint and a knee. Also, Falcon's dash acceleration is better.
His run speed is actually better. I said nothing about dash acceleration.
Sonic's JC grab goes further and can't be ducked.
Sonic's grabs go into more things than Falcon without even trying. Falcon's downthrow goes into tech chases except against floaties, Sonic's downthrow does the same thing but with more time to act and it sends lower for drop zone anything. Falcon's upthrow is situational at best if he can get uair in time, Sonic's upthrow is a hit of most aerials granted % isn't over 100 on a floaty.
Falcon has more disjoint? in what? Certain Sonic's fair and bair will beat all of his moves.
The way Sonic maintains momentum and speed is similar to Falcon in that you need to attack before you are on your opponent. You can rush down with moves to punish whiffed attacks. His momentum also allows him to do fly by moves making them pseudo-safe on shield.
Sonic also has a safer combo weight than Falcon.
Sonic also has better recovery.
I said the characters are similar not the same, you're just being nitpicky. Both characters are similar in that the placement of their moves is difficult because of how they retain momentum. Sonic may not have knee, but you can RAR bair from across the stage and ruin someone's day.