RAID 0 is striping and it means that the same data is split across several disks. In theory, that's double the write/read speed with two disks configured in RAID 0 but you won't get that in practice. You retain the capacity of the individual drives, 2 500GB drives give you 1TB but if one drive in your RAID 0 array fails your whole RAID 0 setup will fail.
RAID 1 is called mirroring and it's a backup system where the second drive is a mirror image of the first drive. 2 500GB drives give you only 500GB of storage.
RAID configurations are often used in tandem but you can't just add a new drive in and expect it to configure itself.