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

Execution · Competitive PvP
Early fighting-game execution and spacing, plus mind-games against humans.

Execution · Grand Arena
A tag-team crossover fighter pitting Street Fighter's cast against Tekken's under Capcom rules.
Art of Fighting 2 leans Execution (Competitive PvP); Street Fighter X Tekken leans Execution (Grand Arena).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Art of Fighting 2
Spirit-gauge specials and spacing demand drilled precision
Street Fighter X Tekken
Tag combos and juggle timing demand practiced hands
Street Fighter X Tekken leans a little harder on reads, though the gap is small.
Art of Fighting 2
Human matches turn on baiting and conditioning
Street Fighter X Tekken
Human mixups and tag baits require adaptation
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Art of Fighting 2
Nothing random in the fixed roster
Street Fighter X Tekken
Deterministic aside from negligible elements
Street Fighter X Tekken leans a little harder on optimization, though the gap is small.
Art of Fighting 2
Notoriously hard AI patterns are studyable scripts, not minds
Street Fighter X Tekken
Gem loadouts and team synergy add a builder layer
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.