In Chicago, "community areas" are generally used to refer to communities/neighborhoods.
"Community Areas" (CAs) are statistical & administrative boundaries designated in 1930s by the University of Chicago sociologists but also used by the City of Chicago government. The boundaries of CAs coincide with those of census tracts, and thus CAs are ideal for generating aggregated statistical information.
"Neighborhoods" are much smaller boundaries generally defined by local residents and the Chicago real estate association.