A ticket should be distinguished from a receipt. Tickets are issued (for cash) particularly for transport or entertainment. They are usually an essential part of the contract and contain conditions of the offer or else refer to the existence of these conditions and state where they are to be found. The contract is not closed until the customer accepts the ticket and hands over the money.
A receipt on the other hand is an acknowledgement of payment of a debt already due and cannot contain further conditions applicable to the contract.

Reference: The Penguin Business Dictionary, 3rd edt.