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
A near-future Call of Duty with squad-focused multiplayer and the Extinction mode.

Execution · Competitive PvP
Tests shot timing and play-calling prediction against human defenders.
Call of Duty: Ghosts leans Execution (Practiced Mastery); NBA 2K15 leans Execution (Competitive PvP).
Call of Duty: Ghosts leans a little harder on execution, though the gap is small.
Call of Duty: Ghosts
Fast time-to-kill rewards first-shot aim
NBA 2K15
Shot-stick timing and dribble moves demand practiced hands
NBA 2K15 leans a little harder on reads, though the gap is small.
Call of Duty: Ghosts
Outguessing human routes and peeks matters
NBA 2K15
Versus humans, baiting defenders and calling counters drives possessions
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Duty: Ghosts
Spawns and lobby matchups add noise
NBA 2K15
Shot RNG and loose balls swing close games
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Duty: Ghosts
Loadout and map knowledge are solvable layers
NBA 2K15
Playbooks, matchups and roster management reward system 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.