As a local, I'll add what I think are more meaningful differences.

First, most homeless people in CA are locals who were forced out, not interstate homeless migrants looking for a good place to be homeless.

The main reason is that CA doesn't have nearly as many temporary shelters for people to go to. And as you noted, it's more survivable to live outdoors.

Overall, NYC still has a pretty big population of folks in shelters, but CA has way more folks living in cars, trailers, and tents.