Originally Posted by Siosilvar
The two sections don't reference each other. Willing might be something that only exists for specific spells if you look at the RAW. For other spells, it's "voluntarily forgo[ing] a saving throw". Does common sense tell us it's the same? Maybe, maybe not.
I'm going to go ahead and support 015: Unconscious does not mean Mindraped until further notice.
No, Willing explicitly doesn't exist only for spells that say (willing only).
When you cast a spell it checks target and then decides what happens. Willing is the most restrictive of the various subsets in targets (everything but objects falls into the creature subset, for example; or everything that is undead falls into the undead subset, which is a part of the creatures subset. So a lich would fall into the Creature (Undead (Intelligent Undead)) set.
The bottom of the set is willing; you become part of that set in only 2 situations, if you choose it or if you are unconscious. Everything that is part of the willing subset gets no save.