prepayment

As nouns the difference between prepayment and advance

is that prepayment is a payment in advance while advance is a forward move; improvement or progression.

As a verb advance is

to bring forward; to move towards the front; to make to go on.

As an adjective advance is

completed before need or a milestone event.

Buydown is a synonym of prepayment.

As nouns the difference between prepayment and buydown

is that prepayment is a payment in advance while buydown is an accelerated repayment of the principal of a loan.