Aeroplan used to be owned by AC, and AC used it to track top-tier passengers. After selling Aeroplan off, AC still used Aeroplan's mileage accrual as a way to track top-tier passengers.

Beginning in 2013, Air Canada has re-started its own in-house top-tier program, Altitude. Those top-tier flyers get Altitude miles, which are only used to qualify for status, as well as Aeroplan miles, which are only used to redeem for flights/etc.

Now Aeroplan has also developed a top-tier program for its own members, the main distinction (haha, get it) being that miles earned by Aeroplan partners (save for some bank/credit card bonuses) are eligible, whereas Altitude counts only miles flown in qualifying fare buckets. The benefits are NOT the same, meaning there are no priority boarding/additional baggage allowance/Star Alliance statuses offered.

The part I really don't like is this: For 2014, E35, E50 and E75 members now have to pay a fee in addition to using their eUpgrade credits in order to upgrade on long-haul international flights. This fee is only charged if the upgrade successfully clears.