if you have the budget go with the bigger drive, you can save alot and get the 840 evo though, allowing funds to go towards other features. the only difference is capacity and probably some benchmark speeds, but nothing that will be noticable in the real world use.
depending on how large the games are, id go with the bigger one to be able to fit those and have room. remember, only fill about 70% of the ssd, then itll start slowing down alot. well, around 70%, i cant remember the exact figure
EDIT: around 80% or 85% can be used without suffering noticable performance drops