What's the difference between a Terminal Control Area and a Control Zone?
A Control Zone is the small (and usually circular) surface area around the airport that is handled by the airport's control tower. At smaller airports (but still large enough to have a tower), this is all they have.

A Terminal Control Area is a large and typically complex area above one or more Control Zones to manage large flows of fast traffic (i.e. airliners) moving in both directions through the congested area between the Control Zone(s) and the en route environment far above.

Note that while Canada (and the US, though it uses very different terminology) often uses the same class of airspace for the TCA and CZ, that isn't required, and there may even be several CZs with different classes under one TCA.