Having played both games, I can definitely say Payday 2 is -not- Left 4 Dead with bank robberies. The maps in PD2 are, admittedly, smaller, but the tasks you have to do are more complicated, there's a distinct stealth element to a number of the missions (even if stealth can be incredibly hard at times) and the selection of weapons is massively bigger. L4D has larger maps, simpler goals and strategies, and no RPG skill elements. This isn't to say they don't share a number of elements, but I think they're different enough to be two distinct types of co-op game.
I admit I haven't watched The Walking Dead yet, but I hear pretty good reviews of it. Overall I'd say if they wanted to make a co-op game set in the franchise, they picked a good stuido to create it.