There is a difference between
Basically you won't find Angels or VCs doing Not For Profit startups. Because by definition, an Angel or VC wants profit. Furthermore NFPs in the USA cannot be controlled by anything but an independent board.
Now if you want to do a social venture startup - you still have to have a solid VC based businessplan. A "share alike" approach isn't going to get many folks interested. In these areas you really are looking for Patrons so something like Patrone.com might be an option