RAID-1
RAID Level 1 provides redundancy by writing all data to two or more drives. The performance of a level 1 array tends to be faster on reads and slower on writes compared to a single drive, but if either drive fails, no data is lost. This is a good entry-level redundant system, since only two drives are required; however, since one drive is used to store a duplicate of the data, the cost per megabyte is high. This level is commonly referred to as mirroring.
So I guess Raid is on the fly real time back up.
Super duper will do a mirror image when you want it to do so. You could use super duper via USB2 to an external hard drive. Raid drives are usually in the same machine and connected together as SATA etc