head to head
Helldivers 2 asks more than Tom Clancy's Rainbow Six: Vegas 2, and the gap is variance.

Optimization · Practiced Mastery
Top-tier co-op shooter against bug and bot hordes.

Execution · Practiced Mastery
A cover-shooter Rainbow Six blending tactical room-clearing with solid gunplay.
Helldivers 2 leans Optimization (Practiced Mastery); Tom Clancy's Rainbow Six: Vegas 2 leans Execution (Practiced Mastery).
Tom Clancy's Rainbow Six: Vegas 2 leans a little harder on execution, though the gap is small.
Helldivers 2
Recoil, stratagem inputs, friendly-fire aim
Tom Clancy's Rainbow Six: Vegas 2
Cover-based gunfights still punish poor aim
Tom Clancy's Rainbow Six: Vegas 2 leans a little harder on reads, though the gap is small.
Helldivers 2
Enemies scripted, no adaptive opponent
Tom Clancy's Rainbow Six: Vegas 2
Multiplayer brings some human adaptation; AI is scripted
Helldivers 2 leans clearly harder on variance.
Helldivers 2
Patrol spawns and modifiers shake missions
Tom Clancy's Rainbow Six: Vegas 2
Enemy placements partially unknown per encounter
Helldivers 2 leans a little harder on optimization, though the gap is small.
Helldivers 2
Loadout and stratagem synergies deep
Tom Clancy's Rainbow Six: Vegas 2
Room-clearing order and squad commands are solvable tactics
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.