I tell the difference between my J and K pop by the, feel, I think?
Because I've listened to J longer, I can understand some of what their saying, or at least recognise it. But with K-pop the entire thing sounds foreign to me (Except maybe Gee, and Saranghae?) and the syllables sound more short and sharp compared to Japanese.
And I've probably listened to all of SNSD, I think the rest of my friends are all nuts about them; they have all those Dvd's or photobooks off ebay or whatnot.
I'm just a sort of passive receptor to whatever sounds good.