"Urban" means "having to do with a city." 

The word "suburb" is a little imprecise. It often means communities that are very close to, but just outside a city. It can also mean communities that are actually part of the outer areas of a city. In any case, they are relatively low population density, may not have tall buildings, has more grass and trees, but are close to a city. "Suburban" means having to do with the suburbs.

"Rural" means "having to do with agriculture and farms," but it can also refer to communities that are far outside a city.

Boston is a major city in the United States.

I do not live in Boston. I live in a suburb of Boston. I live in a house of our own which we do not share with anybody, surrounded by a small piece of land with grass and a garden. It takes me about an hour to get to downtown Boston.

My town is not "rural" because there are no working farms on it, and it is mostly "built up," covered by houses and other buildings.

(For advanced and native speakers only: purists sometimes say that the word "suburb" should refer to communities that are actually inside and part of a city, and that communities just outside a city are properly "exurbs." But in real life I have never heard anybody call anything an "exurb.")

Rural means where agriculture is main source of income of the inhabitant...

Rural means a countryside settlement,urban means a settlement where agriculture is not done by people...Their livelihood comes from commercial activities...

Suburbs means an area which is attached and very closed to urban area....