SC ended up being WTA but only because Trump did so well there. It could have split if the other candidates had qualified for some of the vote (i.e. a 25% threshold or something.)
Winner-takes-all: Statewide delegates are all awarded to #1 (even if #1 has less than 50% of the vote); Three C.D. delegates are all awarded to #1 in the C.D. (even if #1 has less than 50% of the vote).
This is forbidden by the RNC prior to March 15th. But SC was allowed an exception.
Winner-takes-most: Statewide delegates are awarded to all candidates receiving at least 20% of the vote (*). Two C.D. delegates are awarded to #1, and one to #2 in the C.D. (*)
(*) Except if a candidate receives 50% of the vote, then he would be awarded all the delegates.