head to head
Neither is simply harder - they are hard in different places. Diplomacy demands more optimization; Divekick demands more execution.

Reads · Pure Mind Games
A classic strategy game of negotiation and betrayal among nations.

Reads · Pure Mind Games
A two-button parody fighter that strips fighting games down to pure one-hit-kill spacing reads.
Diplomacy leans Reads (Pure Mind Games); Divekick leans Reads (Pure Mind Games).
Divekick leans clearly harder on execution.
Diplomacy
no physical skill, purely negotiation and planning
Divekick
Two buttons, one-hit kills; almost no physical ceiling.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Diplomacy
reading and out-negotiating human players is core
Divekick
Pure spacing yomi against an adapting human is the entire game.
Divekick leans a little harder on variance, though the gap is small.
Diplomacy
no hidden info or randomness, pure information
Divekick
Fully deterministic.
Diplomacy leans clearly harder on optimization.
Diplomacy
strategic alliance and movement planning solvable
Divekick
Character angles and gem choices are quickly mapped.
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.