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
A tennis game testing swing timing, positioning, and anticipating returns.

Execution · Competitive PvP
Execution on the ball plus constant prediction of the other player's shape.
Anna Kournikova's Smash Court Tennis leans Execution (Pure Mechanics); Pro Evolution Soccer 2009 leans Execution (Competitive PvP).
Anna Kournikova's Smash Court Tennis leans a little harder on execution, though the gap is small.
Anna Kournikova's Smash Court Tennis
Timing swings and positioning drive every rally
Pro Evolution Soccer 2009
Close control and finishing windows demand stick precision
Pro Evolution Soccer 2009 leans a little harder on reads, though the gap is small.
Anna Kournikova's Smash Court Tennis
Versus play rewards anticipating opponent shots
Pro Evolution Soccer 2009
Online and couch opponents adjust tactics against you
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Anna Kournikova's Smash Court Tennis
Little randomness in ball physics
Pro Evolution Soccer 2009
Ricochets and keeper parries add small randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Anna Kournikova's Smash Court Tennis
Shot selection and court positioning strategy
Pro Evolution Soccer 2009
Squad setup and tactical sliders reward preparation
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.