RAID 1 is the "mirroring" RAID. Basically, you have multiple hard drives and the data is mirrored onto each HDD (this is good for crucial data; in case one HDD gets corrupted or dies, you still have data on the other HDD; However, you lose a lot of performance)
RAID 0 is the "striping" RAID. This is where the data is divided up equally amongst the HDDs. Say you have 2 HDDs and 20GB of data. 10GB goes to HDD1 and the other 10GB goes to HDD2. You get a good performance boost (GOOD, NOT GREAT), but if one hard drive goes, you lose ALL YOUR DATA.
To sum it all up:
RAID 1 = Reliable but slow
RAID 0 = Fast but risky