The municipalities of the capital region have a legal obligation to cooperate in the areas of waste management and public transport, with HSL being responsible for public transport and HSY for waste management and water supply.

[1] Sometimes the term Greater Helsinki (Finnish: Suur-Helsinki) has been used in the same sense as the Capital region, but not in the official language.

[1] The term Helsinki metropolitan area (Finnish: Helsingin seutu) may be broader than the capital region in common parlance, but it also has a precise meaning in the official language.

For example, when the term Helsinki metropolitan area is used in statistics, it includes 14 municipalities, namely Helsinki, Espoo, Kauniainen, Vantaa, Kirkkonummi, Vihti, Nurmijärvi, Tuusula, Kerava, Järvenpää, Hyvinkää, Mäntsälä, Pornainen and Sipoo.

[1] The Helsinki sub-region (Finnish: Helsingin seutukunta), which is related to the national regional division that was abolished at the beginning of 2014, must be distinguished from the Helsinki metropolitan area.