In medieval England a city could hold a market, but in order for a town to do so, they had to obtain a special permit from the Crown, which would specify when, how often and for how long they could hold the market and what could and could not be sold there. The bestowal of a market charter on Stratford-Upon-Avon helped the town to become relatively prosperous (although it did have it's hards times, most notably during Shakespeare's lifetime when a series of fires destroyed parts of the town; a series of bad crops meant drastic food shortages; and the secularization of the area led to control by Lord Grenville and his descendants, who treated the area as their own personal play pen for two to three generations).
Oh yes, the difference between a city and a town: in England in order for an area to be considered a city it must have a C of E (Church of England) cathedral. One of the smallest Cathedral Cities in England is Durham, in the North, which actually has a smaller population than the town of Royal Lemmington Spa, which is larger but is not a city, and has a Catholic cathedral, but not one of the a C of E.
In case you don't know, the difference between a cathedral and a church is that a cathedral is the seat of a Bishop or Archbishop. The name comes from the latin word cathedra which means seat. In a cathedral there is a Chapter House where a chapter from the bible is read daily and discussed, at the end of this room is the cathedra, the Bishops chair.
