Some neighborhoods are parts of cities. A city is a very large community. It may have thousands or even millions of people. Most cities have a downtown with many tall buildings. Other neighborhoods have homes and businesses. A city and the communities around it make up a metropolitan area.
All the text in this series (City, Small Town, Suburb) is really similar. The latter two books are really great because there aren't many informational texts about Suburbs and such, but this one is just so-so because there are so many other neat books about cities. But because the format is so similar, using this series would be great fora lesson on comparison and contrast.