The way I remember it is:

INIT_LIST_HEAD is of form VERB_NOUN so is called from within a function to programatically initialise the list.

LIST_HEAD_INIT is NOUN_VERB and is used within a structure initialiser not from a function.

But my main point was to show the "embed the list in the data" approach rather than "embed the data in the list" or "point to the data from the list" and not to discuss the naming details in the kernel implementation of the concept.