The critical differences between Falcon 9 first stage and the Starship booster is that Starship booster lands using 3 engines rather than 1, and can throttle them down much further. 3 vs 1 gives Starship more directional control for precise landing (critical for this "catch" maneuver), and throttling allows it to hover, as it does right before the "catch".
But as far as I know, one Merlin engine produces more thrust than the empty booster weighs which means they have to time things perfectly to get to zero velocity exactly at the ground.
Super heavy can hover and even go down by throttling down more. This gives them more control for the landing and don’t have to time it exactly perfectly
