care to elaborate on the differences?
Salvage was breaking of bricks and weapon spawns to use on your own base, which others would attempt to raid and take from you.
Survival was a start-with-nothing grind for a long time to build up a base, get better equipment for it and such.
Martial law, iirc, was a game in which you'd scavenge for items and resources to build a base and build machinery.
They're all similar in that they have base building, but more separates them than just a weapon pack.
