I have just across an appearance by Dr. Edward Philips at:
http://www.cosmeticdentistryto.com/television_mov2.shtml
He mentions that bleaching and whitening are different.

He says that:
Bleaching puts in an artificial colour.
Whitening just dissolves the unnatural yellow pigment leaving you a natural
white behind.

I take it that whitening is the use of carbamide peroxide and/or hydrogen
peroxide gels. So how does one bleach teeth? I.e. introduce an artificial
colour?