What is the difference in WD5000BPVT hard drives with model ending with -22HXZT1 and -00HXZT1?

WD Internal Drives Desktop & Mobile Drives
3

The model number suffix is a Customer Configuration Code. The first two characters are the Merchant ID.

00 = Generic (retail version)
22 = Acer ???

See http://community.wd.com/t5/Desktop-Mobile-Drives/Product-number-help/m-p/274980#M7201