saint nick comes tonight, whoever he is

oh man, I DON'T KNOW! so, okay, tonight (Dec. 5th), saint nick comes to put a couple little treats (usually candy, a little toy, and an orange) in your stocking if you have been good. if not you get coal (for making a snowman! yay!), OR (so i've read) if you've been very bad, a spanking, and if you've been REALLY bad, he will take you away in a sack. sleep tight, kids!
anyhoo, we've always celebrated st nick's growing up (apparently a regional thing, who knew?) but i don't know: are saint nick and santa claus the same? or are they pals? brothers? acquaintances? rivals? saint nicholas rides a white horse, santa has a sleigh with reindeer. cripes. i think i'm going with brothers (which i have just totally made up). is it too early for egg nog?
help me out, people!!