Blue has a 2 year warranty, Black has a 5 year. Black are slated at 7200 RPM, but are 10-15% faster than other 7200 RPM hard drives. Blue is considered average, Black is considered Elite. Blue is not that much cheaper than Black unless you buy it on sale. Right now Newegg has the Blue for $30 off, which I am about to buy 2. There is very little real world difference in blue vs black. If you are looking for speed you should get a SSD anyway, and have a HDD as storage.