Neither of them is particularly inappropriate. Using your Kiwi system, I would probably give them both M or R13- I don't quite understand, what does the M mean? I know in Australia it's basically "no little kids!", but then they only have that, PG, G and MA15+, so if I'm correct:
G- Everyone.
PGR (PG?)- Project Gotham Racing, OR kids who are 6+
M- Kids who are 10+
And the others are obvious. If one is higher than the other, I would rate inFamous higher because it has just as much bad language, and you have the option to be an evil bastard and kill everything in sight. Uncharted has more blood, but what is blood except a spray of red pixels? I would give M to both- neither has enough objectionable content for the law to protect children from them.
(Former) Lead Moderator and (Eternal) VGC Detective 
