What makes white chili white; is it just the lack of tomatoes, substitution of broth for tomato base? I am working on a vegan mushroom based chili and am wondering if it would technically be a (chili) or more accurately a soup/stew.
My understanding is that what many people call white chili would be considered a green chile stew in a place like New Mexico. It's not red in color because it doesn't have any significant amount of dried red chile in it--it gets whatever heat and chile flavor it has from green chile, which doesn't color the stew significantly.
As to defining chili, I think you could work on a definition forever. Apart from the notion that a chile is the pepper, which is the main ingredient, and chili is the dish, I don't like to define it too carefully (of course, New Mexicans think the dish is chile too, but what they have is different from Texas chili, even when they use red chiles).
I think chili is a stew, though. Most stew isn't chili, but all chili is stew. And I believe that for most people to accept what you're making as chili, it would have to include a significant dose of dried red chile powder.
So if you can accept the validity of white chili at all, and what you're making has almost all green chiles and very little red chile, then I'd say you're making a white chili. Or a green chile stew--which would be my preferential term in this case.
In my experience there are two key differences between "regular chili" and "white chili":
white chili is basically a collection of good bits in a spicy and, often, creamy sauce.
All of those bits are light colored, or at least don't leech any color to the sauce.
White chili typically also seems to have a different style of heat... cumin, cilantro, fresh green chiles, etc.
And while I wouldn't disagree about pork based chili being able to be white... I don't think I've ever seen one... they're almost always poultry or seafood (rare, but I have seen it a couple times during lent) if they aren't vegetarian.