I would argue that L4D is far more innovative then LBP. The difference is however the innovativeness is harder to detect since it's through the director AI.
LBP is basically copying a number of computer games, and making it simplier to interface by cutting back your options and giving you limited creativeness in the hope that enough people will buy it that it isn't just regulated to people making levels and practically begging others to play them.
L4D is by for the more important innovation as well because it's one step away from procedural AI for enemies... and that will be a glorius day. When every computer soldier of a class doesn't react the same way... or of whatever.








