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 · Pure Mechanics
Comic-panel beat 'em up notorious for punishing health drain and tough fights.

Execution · Pure Mechanics
A cover-based run-and-gun testing precise shooting and pattern memorization.
Comix Zone leans Execution (Pure Mechanics); Rolling Thunder 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.
Comix Zone
Brutal one-life brawling demands clean play
Rolling Thunder 2
Precise shooting, cover-jumping and timing carry every stage
Rolling Thunder 2 leans a little harder on reads, though the gap is small.
Comix Zone
Enemies follow fixed attack scripts
Rolling Thunder 2
Solo/co-op - enemies follow scripted spawn patterns
Rolling Thunder 2 leans a little harder on variance, though the gap is small.
Comix Zone
Everything is placed and scripted
Rolling Thunder 2
Enemy appearances are fixed once memorized
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Comix Zone
Panel routes and item use are memorizable
Rolling Thunder 2
Learning spawn points and weapon management is the meta-game
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.