head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Execution · Pure Mechanics
The refined sequel adding freestyle scratching and head-to-head DJ battles to the turntable formula.

Execution · Pure Mechanics
The full-band rhythm game whose setlist and feel made it the genre's high-water mark.
DJ Hero 2 leans Execution (Pure Mechanics); Rock Band 2 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.
DJ Hero 2
Faster scratch patterns plus freestyle sections
Rock Band 2
Guitar, drum, and vocal accuracy on expert charts
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
DJ Hero 2
No adaptive element
Rock Band 2
Charts never respond
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
DJ Hero 2
Charts fixed despite freestyle windows
Rock Band 2
Fixed setlist charts
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
DJ Hero 2
Score multiplier and euphoria routing
Rock Band 2
Overdrive activation paths decide leaderboard 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.