Huh. I really wish there was more information. The best I can find, aside from forums, is the wikipedia page that describes tulpas as a mystic/religious phenomenon, heh. (
http://en.wikipedia.org/wiki/Tulpa)
The forum thread that AdamMZ linked to (
http://hamumu.com/forum/showthread.php?t=23892) describes them as being separate from alters. They don't go into why exactly they feel tulpas are separate from DID (and don't seem to know much about DID, they even call it MPD), though, so I have no idea if their view is accurate (from the link):
"
What is a tulpa?
The dictionary definition is "a being or object that is created in the imagination by visualization techniques such as in Tibetan mysticism".
Practically, a tulpa is, in essence, an imaginary friend that you create for yourself. They can interact with all five bodily senses (in addition to a couple more that I am not going to bother explaining here). This means you can see, hear, touch, smell, and (ew) taste them. Although a tulpa is based entirely in your mind, it is set in the subconscious to allow them to exist and operate without your attention and focus.
A tulpa is fully sentient, self-aware, and has its own personality, thought process, and likes/dislikes. They have unique appearances, voices, scents, and personalities, which they can change at any time.
Now, you may be thinking; "Isn't this like schizophrenia or multiple personality disorder (MPD)?"
No. This is nothing of the sort. Schizo is a psychotic disorder which distorts the senses and may give you false stimuli. A tulpa interacts with the world as it should, unless you specifically tell them to ignore a certain law of physics (such as gravity). You cannot contract MPD from a tulpa, as they are a completely separate entity. You will never be taken over by your tulpa, and cannot, except for a long and complicated process known as "switching" or on smaller scales "possession". This process is voluntary and takes several weeks, if not months, of work."
(There's more, but it's long, so I didn't put it all here.)
Which I guess just brings me back to my question to AdamMZ about what his personal definition and experience is. Though that's mostly curiosity - I still feel a trained therapist is the only one who can really help him definitively sort this out. Though I suspect finding a therapist who knows about and has experience with tulpas
and DID might be almost impossible. I suppose I'd recommend bringing information to a good DID therapist and describing your personal experiences, AdamMZ.
Edited to correct a typo.