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 · Pure Mechanics
The Guitar Hero entry that added drums and vocals to chase full-band play.

Execution · Pure Mechanics
Rhythm FPS where every shot must land on the metal soundtrack's beat.
Guitar Hero: World Tour leans Execution (Pure Mechanics); Metal: Hellsinger leans Execution (Pure Mechanics).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Guitar Hero: World Tour
Fret-and-strum accuracy on expert note charts
Metal: Hellsinger
shooting on the beat is the entire skill test
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Guitar Hero: World Tour
Charts never adapt
Metal: Hellsinger
demons follow fixed behavior
Metal: Hellsinger leans a little harder on variance, though the gap is small.
Guitar Hero: World Tour
Deterministic charts
Metal: Hellsinger
deterministic arenas
Metal: Hellsinger leans a little harder on optimization, though the gap is small.
Guitar Hero: World Tour
Star power activation paths drive top scores
Metal: Hellsinger
weapon choice and streak management for scores
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.