Someone you share a genuine friendshipwith that you also happen to be able to engage in sexual relations with, without having any commitment or ties to one another.
We are just FWB, we're able to explore sexual relations without the extra feelings, emotions and commitments while still being just the homies.
Translation-Friends with benefits- the wordsbasically explains itself... Friends that are usually both single; that do "stuff" together as in sex, making out etc.
casual relationship implying no committment, but involving companionship (the friends bit) and some sort of physical element like making out, sex, baseball (the benefits). although rumored to be a myth, absolutely possible.