When you buy a car you have all the money upfront ready either in cash, check, etc. Leasing is when you have a little bit or most of the money. Because you dont have all of it you pay for the car monthly and pay a little bit more than the actual value of the car as interest for "borrowing" their money since you couldn't afford the entire value of the car upfront. The more money you put down at the time of leasing, the less the interest usually is.
