IDE is a type of Hard Drive that referrs to the BUS/Transfer technolgoy - Hard Drives can be IDE or SCSI.

RAID stands for Redundant Array of Independant (or Inexpensive) Disk

RAID is basically 2 or more disk configured in a way so that Windows see ony 1 disk when there are multiple underlying disc that are configured so that the data is spread across all the disc so that if one disc fails you can recover the data.