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

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

Execution · Pure Mechanics
Momentum-perfect platform racing spiced with item mind games against humans.
Micro Machines 2: Turbo Tournament leans Execution (Pure Mechanics); SpeedRunners leans Execution (Pure Mechanics).
SpeedRunners leans a little harder on execution, though the gap is small.
Micro Machines 2: Turbo Tournament
Twitchy top-down handling on tabletop tracks is the core test
SpeedRunners
Grapple swings and boost timing at full speed decide races
SpeedRunners leans a little harder on reads, though the gap is small.
Micro Machines 2: Turbo Tournament
Screen-edge duels reward predicting human rivals' lines
SpeedRunners
Timing item throws against human racers' habits wins exchanges
SpeedRunners leans a little harder on variance, though the gap is small.
Micro Machines 2: Turbo Tournament
Tracks fixed, almost nothing random
SpeedRunners
Item pickups add party-game chaos
SpeedRunners leans a little harder on optimization, though the gap is small.
Micro Machines 2: Turbo Tournament
Memorising shortcuts and racing lines per track
SpeedRunners
Optimal racing lines per track 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.