Population and Housing

[jamincan]

Statistics Canada provides a Census Dictionary

In brief, a CMA is made up of constituent Census Subdivisions (which correspond to municipal boundaries) centered on a core population centre. Outlying CSDs are included in the CMA when at least 50% of residents work in the core, or 50% of its labour force live in the core. There are a bunch of additional rules, but that is the basic gist of it.

Economic Regions are set in collaboration with provinces and generally fall along Census Division lines (which correspond to upper-level municipal boundaries). I'm not sure the exact rationale, but the provincial government generally breaks down the province into 6 major regions - GTA, Central, East, Southwest, Northeast and Northwest. The Statistics Canada Economic Regions correspond to those larger regions, and seem to allow smaller sub-regions to be examined within them:
Southwest -> Windsor-Sarnia, London, and Stratford-Bruce Peninsula
Central -> Hamilton-Niagara Peninsula, Kitchener-Waterloo-Barrie, and Muskoka-Kawarthas
GTA -> Toronto
East -> Kingston-Pembroke, Ottawa
Northeast -> Northeast
Northwest -> Northwest