From a purely subjective point of view that's a fair enough assessment. However though they may share genre space(FPS), they begin to diverge in regards to the specific type of gameplay each employs.
Specifically the two very different damage profiles, and thus play styles weigh heavily into what type of strategies a player employs, especially in regards to competitive multiplayer, and even while they both may be FPSs, they are actually quite difficult to compare each other to.
Aside from that if I'm going be a little subjective, from my own experience in both game series, the Halo Series in team-oriented gametypes, lends itself better to actual team-tactics, and the playstyle also encourages more cooperative thinking in regards to goals.