DIFFERENCE BETWEEN A CITY AND A TOWN IN THE COMMONWEALTH OF MASSACHUSETTS

But what exactly is the difference between cities and towns? In Massachusetts, the essential difference is structural: a city is defined by the presence of a city or town council as the alternative legislative body to a town meeting. Having a mayor as the chief executive officer is optional though predominant in the state, this role being present in 43 cities (77%). Chelsea, Cambridge, Lowell and Worcester each have as their chief executive officer a city manager, who is appointed by and reports to the elected city council. 

While the latter three cities also have mayors, they hold only ceremonial positions. 

Additionally, there are eight "Town of" cities that have town managers and one with a town administrator. 

https://www.mass.gov/files/documents/2017/09/19/16ctown-july21.pdf