gimp.image_list() vs pdb.gimp_image_list()

[DebianFanatic]

➤> pdb.gimp_image_list()
(1, (1,))

➤> gimp.image_list()
[<gimp.Image '[KentsHouse-FamInDen] (imported)'>]

Obviously two different commands (procedures? attributes? properties?), despite their similar names.

The Python Console "Browse" button shows info about pdb.gimp_image_list(), but seems to know nothing about the other. Where is this other command coming from (if not GIMP's internal Procedure DataBase), and how would I know about it if I hadn't just stumbled onto it?

--
Kent