art exhibits and art fairs sell art, therefore it's perhaps maybe not exactly the differentiation. 

With 2 fair editions held annually, Affordable Art-Fair New York gives visitors the chance to browse first contemporary paintings, sculptures, prints and photographs. The exhibit or list includes fresh galleries making their Affordable Art Fair New York City debut. A number of these brand new galleries hail by the USA, promising a diverse overview of the American contemporary art landscape in the fair this past year. https://www.nytimes.com/2016/10/21/arts/design/9-rarities-appearing-at-a-new-york-art-fairs-debut.html