SATA is just a new type of hard drive connector basically. Drives used to use IDE cables/interfaces, now use SATA cables/interfaces. There's a theoretical speed increase there as well, but really the main difference right now is the cable you use.
RAID is a system of using 2 hard drives together to either a) make 1 large hard drive out of the 2, and/or b) Have the drives mirror each other so there is constnatly backups of your data being made on both hard drives (in case one dies). There are other uses as well, but that's the gist.