buy rate
The rate a bank or exchange booth uses when it buys foreign money from you (you get Canadian dollars back).
sell rate
The rate a bank or exchange booth uses when it sells foreign money to you (you pay Canadian dollars).
spread
The difference between the sell rate and the buy rate. It's one way exchange businesses earn money.
foreign transaction fee
An extra charge some cards add when you pay in another currency, often a percent of the purchase.
commission
A fee charged for a service, like exchanging money.