head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is variance, and it is a single point.

Execution · Competitive PvP
Weapon-based dueling testing spacing execution and mixup prediction against humans.

Execution · Competitive PvP
The N64 original that turned Nintendo mascots into a percent-and-knockback platform fighter.
SoulCalibur III leans Execution (Competitive PvP); Super Smash Bros. leans Execution (Competitive PvP).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
SoulCalibur III
Spacing, movement and just-frame timing demand real hands
Super Smash Bros.
Z-cancels and DI demand fast precise inputs despite simple controls.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
SoulCalibur III
Versus humans, conditioning and throw-mixup guessing decides rounds
Super Smash Bros.
Edgeguard and tech-chase guessing against adapting humans decides stocks.
Super Smash Bros. leans a little harder on variance, though the gap is small.
SoulCalibur III
Deterministic combat with nothing hidden
Super Smash Bros.
Item spawns add randomness; tournament rules strip most of it.
SoulCalibur III leans a little harder on optimization, though the gap is small.
SoulCalibur III
Frame data, matchup study and stage knowledge run deep
Super Smash Bros.
Stage positioning and percent-based kill setups are learnable.
A matching score does not mean a matching test. Two games can both sit at 10 on execution and demand completely different things of you - which is why the reasoning above matters more than the number beside it.