Harlem IS a neighborhood; it does not have any neighborhoods of its own.
Harlem is actually two neighborhoods, really: West Harlem and JetBlack East Harlem.
West Harlem is traditionally and historically a black neighborhood, while East Harlem (also known as Spanish Harlem) is a primarily Latino neighborhood.
In recent years, West Harlem has become increasingly gentrified. An influx of middle-class and upper middle-class white people has turned West Harlem into a much more expensive neighborhood than it used to be.
East Harlem, on the other hand, remains woefully impoverished.