HI
Rebate is a partial repayment, whereas a refund is a repayment of the total purchase price
Discount is reduction in Price
or
Discount means ...it happens on a single purchase...when comes to rebate .....it happens on only after some particular period of time.
Rebate: an incentive to be given to a customer. Clubbed with qty purchased by a customer within the period specified (say one month)-conditional.
Discount: unconditional, to be given to a customer on account of heavy purchase by one single billing.-From the price List(Base price).
Or
Rebate is given for the purchase of specified quantity or on the volume of the sales over a given period of time.
Discount is given on every  goods purchased by the customer
Or
Rebate is a retroactive agreement. it is given to a partial payment to particular scheduled time.(1yr or 3 Yr).
Discount is given at a time to the customer.
