The key difference between a professional association and a union is that a professional association works to promote the industry/profession as a whole, while a union works to promote the interests of the workers it represents in-collective bargaining. This may seem like a difference without a distinction, but it’s important when looking at what activities a professional association can and cannot engage in. While unions actively  advocate for their members’ personal financial interests and specific terms and conditions of employment, professional associations  work to improve public perception of an industry or professional, e.g.,  through the establishment of standards and informing government  decisions. Also, as discussed below, unions have the protection of the “labor exemption” to the antitrust laws.