Air Conditioner - Closed vs Exhaust?

Question:I have an air conditioner in the window of my house. The 'Vent Control' has the options that if I slide the control to the left, it is "Closed"...to the right is "Exhaust". What is the difference between the two, I don't notice a difference.

Answers:
closed means it does not pull air from the outside

Exhaust means there is a small flap just in side of the unit most of the time you can look tho the vents and see it in that mode it opens that flap up drawing in air from the outside