From my experience on these matters, they’ll say that the Black Students Association is open to students of all races (i.e., non-blacks are not expressly banned from joining in the club’s by-laws), while the KoC’s membership is expressly reserved for Catholic men. When I was in college, the university threatened to take away the College Republicans’ school charter if we didn’t change the by-laws to allow *registered Democrats* to join; I quit the club when members voted to capitulate.
Sad when people give in to their ideals.