I don't think its fair to compare these two games. Since it are two different beasts
My 5 cents (based on the fact that in Halo 4 i only played TDM whereas in BO2 I only play domination)
Halo 4 is more fair in its deaths. since most player have the same equipment and there are only limited weapons, its far easier to understand when you die why you died (using long range weapon against and smg in cqb ie).
BO2 (and all other COD games) are much more unfair, since you can be quickscoped, killed by killstreak, exploding car, mines, campers etc
However BO2 (and COD) offers more variation: you can equip a pistol only class, create a weird class and have fun with it. You can't do that in halo with its limited weapons.
You can not really compare the two, although it seams 343 is trying to make it more like COD. I love all the past Halo games but Halo 4 sucks. Active Camo + Shotgun, Active Camo + Sniper. Besides the guys hiding from invisibility the game is a DMR, BR spam fest. 343 ruined the Halo series.
Just played it today and it was ridiculous put Black ops 2 back in and what a relief.....
halo isnt like cod. Halo is "aim for the head" cod is "aim for the chest". halo is teamwork (well... it used to be ALL about teamwork back in halo 2... i miss those days. but the reason I say teamwork, is cause well... in CoD if you turn the corner and there are 4 of em... you have a chance in hell of winning. in halo.... your chances of surviving are almost null. and if you did... its cause they sucked.), CoD is lonewolf.
The lone wolf aspect is why I've always enjoyed COD games. However, there is an active move to make this a strictly team based game.
And on that token, the fact is that if a team of six really wanted to work as a team, there are things set up in every COD since MW2 so that genuine, real team work could decimate opposing teams. The only two aspects of the game I've seen used by clans/parties/teams is communication and/or simply having good lone wolf players on the same team. That's generally enough to score wins, but I really think 75 - 10 scores in TDM are fully possible utilizing those two aspects as well as the in-game items.
COD still has an element of lone wolf, sure. But that's rapidly changing.