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

Execution · Pure Mechanics
Twitchy miniature racing where screen-edge duels punish imprecise hands.

Execution · Competitive PvP
Wrestling crude controls to land specials while outguessing a human opponent.
Micro Machines 2: Turbo Tournament leans Execution (Pure Mechanics); Street Fighter 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.
Micro Machines 2: Turbo Tournament
Twitchy top-down handling on tabletop tracks is the core test
Street Fighter
Notoriously stiff inputs make landing specials the real fight
Street Fighter leans a little harder on reads, though the gap is small.
Micro Machines 2: Turbo Tournament
Screen-edge duels reward predicting human rivals' lines
Street Fighter
Human versus rounds still reward bait and punish
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Micro Machines 2: Turbo Tournament
Tracks fixed, almost nothing random
Street Fighter
Nothing hidden between two visible fighters
Micro Machines 2: Turbo Tournament leans a little harder on optimization, though the gap is small.
Micro Machines 2: Turbo Tournament
Memorising shortcuts and racing lines per track
Street Fighter
Tiny moveset leaves little system to solve
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.