Now I'm curious, what do they mean in America? As a Canadian I think both words describe a single unit in a multi-story building, but say "apartment" if the entire building is owned by one company and all units are rented, and "condo" if each unit is sold to an individual owner (who may still rent it out privately if they want). I rent an apartment, I'd buy a condo. They're physically the same thing, just different ownership models. Most Canadians I know (Vancouver/Calgary) do the same.
What I have encountered is that the word apartment is accepted for any residential unit while words that specifically relate to the nature of occupancy are not always used because that may be ambiguous. Is an apartment the only residential unit in the building? Is an apartment a condo, joint or fractional ownership, rental, or timeshare? All of these tend to be referred to casually as apartments unless more is known and needs to be communicated.
In the market of people who would buy a house / condo with the proceeds of their job, you will see the cheap stuff bought first and go up in price while expensive stuff goes down until they reach an equilibrium point of pricing of whatever people can afford.
Yes, Vancouver downtown apartments were $1200/sq feet. Apparently you need at least $1 million US dollars to have a family of four living in downtown Vancouver. Crazy huh.