>>19018342The differences are very minor, with the exception of the Pokemon on the front cover.
In X, Xerneus plays a role in the storyline, whereas in Y it's Yveltal. Just pick whichever one looks prettier, and go with it.
You can trade for the other if you plan on catching them all, so you don't need to worry about having to choose one of the other.
And yes, X/Y are the latest games in the series.