My HP printer using 'HP 862 ink cartridge' -- at least the label of it says so. So I've searched the '862' on hp.com
The web site says there are 3 black 862 ink cartridge:
862 black photo
The 'XL' one is said to be filled more ink than normal one, and there is no more description for the difference between '862 black' and '862 black photo'. Unfortunately for I thought 'the Photo Black may be optimised for PHOTOs', and bought the photo black.
BUT! In fact the '862 black' is entirely different than '862 black photo', my printer is NOT compatible with the latter!!