LATENCY

Endogenic and Willowgenic are two different forms of system origin. They are both types of systems who formed without trauma.

Polyminds are not systems. They are people whose subpersonalities are extremely different from each other. Subpersonalities are differences in your personality based on your situation. Ex: spending time with friends vs working. Essentially everyone has them. Polyminds give these subpersonalities names, roles, etc.

(I don't know as much about this one, so I may be wrong, but) Tulpas are essentially people who "create" beings in their heads. They start by imagining a body and personality for them, as well as thinking thoughts for them, before this being (known as a thoughtform) can move and think on their own.

Tulpas have been a practice for centuries, and have been studied. Polyminds, Willows and Endos have never been medically recognized, as far as I'm aware, although subpersonalities have been.