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 · Practiced Mastery
Demanding platform execution plus a solvable boss-weakness ordering puzzle.

Execution · Pure Mechanics
Brutal one-hit-death shmup execution over patterns that must be memorised to survive.
Mega Man leans Execution (Practiced Mastery); Silver Surfer leans Execution (Pure Mechanics).
Silver Surfer leans a little harder on execution, though the gap is small.
Mega Man
Pixel-precise jumps and shots against brutal fixed stages
Silver Surfer
One-hit deaths demand near-perfect dodging every second
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Mega Man
Robot Masters cycle rigid scripted patterns
Silver Surfer
Enemy waves are fully scripted patterns
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Mega Man
Nothing changes between attempts
Silver Surfer
Stages replay identically once learned
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Mega Man
Boss-order weakness routing is a known solvable layer
Silver Surfer
Memorising spawn patterns and safe lines is mandatory study
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.