People deposit their extra cash in bank. A bank in addition to keeping the money also pays interest on the deposit to the depositor. Thus bank deposits are also called demand deposits.
A person simply needs to have an account with the bank to deposit money. A cheque can be used to make payment directly from a bank deposit without using cash.
A cheque is a written instruction to a bank by an account holder to pay a specific sum to a specific person from his deposit. A cheque has all the information about the person to whom payment is to be made, the amount and date of payment and signature of account holder issuing the cheque.