Town
A town is a urban area where a large human population is concentrated and whose space is designed to facilitate and concentrate these activities: housing, commerce, industry, education, politics, culture, [URL=/help/org/urban:town][…][/URL]
. Sphere: territorial. Prerequisite: Village. Possible outlets: Lordship / Sheikhdom / Barony / Vidamy / Viscounty / Burgraviate / City.
City
A city is an administrative or honorific status attributed to a human settlement that is generally more populous than a town according to local rules. [URL=/help/org/urban:city][…][/URL]
. Sphere: territorial. Prerequisite: Town. Possible outlets: City-state.
District
A district is a type of administrative and territorial division that is managed by a local government, and generally includes several cities or towns. [URL=/help/org/urban:district][…][/URL]
Sphere: temporal. 240 arpents.
Possible outlets: County / Principality / Emirate / Federation / Viceroyalty / Sultanate / Caliphate.
City-state 
A city-state or free city is a city governed by itself and subjected only to the King or to the Emperor. The governor of a city-state receives the title of Doge, equivalent to a duke. [URL=/help/org/urban:citystat][…][/URL]
. Sphere: territorial and temporal. Prerequisite: City.