The census divisions of Ontario are used by Statistics Canada to aggregate census data. With two exceptions, they correspond to Ontario's first-level administrative divisions, of which there are three types: single-tier municipalities, upper-tier municipalities (which can be regional municipalities or counties), and districts. These differ primarily in the services that they provide to their residents, and their different structures result from the vast disparities among Ontario's different regions. They may comprise smaller municipalities or other types of administrative divisions, which are generally treated as census subdivisions by Statistics Canada.