We shall begin with a logic exercise:
All 501(c)(3) organizations are nonprofit organizations. All 501(c)(3) organizations are tax-exempt. Not all nonprofit organizations are 501(c)(3) organizations OR tax-exempt. And not all tax-exempt organizations are 501(c)(3) organizations. Many people use these terms or phrases interchangeably but they actually are NOT synonymous.
A nonprofit organization is any entity (corporation, limited liability company, etc.) that essentially does not operate to earn a profit. Oftentimes, these organizations fund their activities and operations and use remaining revenue to benefit some public interest in line with their missions. Nonprofit organizations, as is the case with all organizations and businesses, are organized at the state level and do not necessarily have a federal income tax exemption (under section 501(c) of the Internal Revenue Code (IRC)). Some have state tax exemptions and there are some that do not have any federal or state tax-exempt status at all. The most well-known and popular exempt status is the 501(c)(3) however there are others. These exemptions allow organizations to not pay taxes on their income.