head to head
Marathon asks more than Battlefield 1, and the gap is variance.

Execution · Competitive PvP
WWI conquest shooter with weighty gunplay.

Execution · Competitive PvP
Aim duels against human crews layered over hidden-information loot gambles and extraction timing.
Battlefield 1 leans Execution (Competitive PvP); Marathon leans Execution (Competitive PvP).
Marathon leans a little harder on execution, though the gap is small.
Battlefield 1
Bolt-actions reward steady aim and timing
Marathon
Gunfights against other crews reward raw aim heavily
Marathon leans a little harder on reads, though the gap is small.
Battlefield 1
Trench flanks and gas plays beat predictions
Marathon
Predicting human crews' rotations and ambushes is constant
Marathon leans clearly harder on variance.
Battlefield 1
Behemoth spawns and chaos shift matches
Marathon
Loot spawns and unseen squads create hidden information
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Battlefield 1
Class kits and vehicle counters matter
Marathon
Loadout economics and extraction routing sit underneath
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.