The difference between a formal and a vernacular region is that

Difference between a formal and a vernacular region:

Formal region:

A formal region is confined to a set of people who have one or more things in common.Formal region is the area inhabited by a set of people who have characteristics in common. In a city there can be one formal region.Example: Europe, Africa, United States.

Vernacular region:

A vernacular region is 'based on people's perception' of culture. A vernacular region is an 'area which is divided based on certain criteria be it culture'.In a city there can be number of vernacular regionsExample of vernacular region is South California, New York City, Gold Coast etc.

Ca mega city if i’m not mistaken