passive skills are skills that you dont need to activate and they dont use your mp, they just are

[like when your masteries are lvl 10 you get that passive skill that is in the end of your skill list, like +hp(heuksal) or +atk. rating(bow)] they just boost your stats forever.
buffs are skills that increase your def or atk in eighter magical or physical (like frost guard (phy.def) or flame body (phy.atk). some buffs even encrease moving speed (like ghost walk). buffs dont last forever which makes them different from passive skills, they last a certain time.
so yeah passive skills are skills that boost your stats forever (without you needing to activate them) and buff boost your stats for a certain time and when that time is up they "deactivate" and you have to "activate" them again
well thats about it i think, this is the best i could come up with in the morning
