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
Tests NES-hard execution and rote memorisation of brutal fixed stages.

Execution · Practiced Mastery
Crowd-control execution against memorised enemy patterns, stage by stage.
Battletoads / Double Dragon leans Execution (Pure Mechanics); Streets of Rage leans Execution (Practiced Mastery).
Battletoads / Double Dragon leans a little harder on execution, though the gap is small.
Battletoads / Double Dragon
Unforgiving brawls and vehicle stages punish any input slip
Streets of Rage
Spacing, crowd control and throw timing carry every stage
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Battletoads / Double Dragon
Enemies run fixed NES-era scripts
Streets of Rage
Enemy gangs attack from fixed arcade patterns
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Battletoads / Double Dragon
Everything is deterministic once stages are memorised
Streets of Rage
Spawns are essentially deterministic per stage
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Battletoads / Double Dragon
Memorising stage layouts and enemy spawns is mandatory progress
Streets of Rage
One-credit clears come from learned positioning and patterns
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.