Is there a difference between a nonprofit and a non-for-profit? Some say so, some say no. I revised the “Nonprofit v. Not-for-Profit” section of the Nonprofit Organizations entry to clarify the distinction.
As I understand it, some people think of a “nonprofit” as a tax-exempt organization with a charitable purpose, while a “not-for-profit” is a taxable entity that may make a profit but does not distribute the profit to its owners (see e.g., New York State’s Not-for-Profit Corporation law). I’m not sure how much overlap there could be between the two concepts.
I’m even less sure how much “nonprofits” and “not-for-profits” overlap with “charities” and “tax-exempt organizations.” I’ll sort it all out some day, when I retire and write Zimmerman’s Legal Research Dictionary.