The standard 5.56x45 round with the 62 grain steel core projectile masses about 200 grams. The standard 7.62x51 round with a 147 grain projectile masses about twice that. A 10kG loadout of 5.56 is about 660 rounds. 10kG of 7.62 is about 280 rounds (including magazines). So, logistically, you can transport MORE than twice the number of 5.56 rounds for the same weight.
The 7.62 is, without a doubt, more lethal. Double? How do you quantify that?
Accuracy at <300 meters is about equal. Beyond 300 meters, the 7.62 is superior.
Don't have any information regarding cookoff, but I'd imagine they're similar.
The 5.56 is considerably less expensive per cartridge - to the tune of about half the cost of 7.62 or less.
TLDR, 7.62 is more lethal and better on long range than the 5.56 but requires more effort for logistics to transport, also it's more expensive.