the downpayment does not reduce the principal until the termination of the contract, meaning that if you put a 25% downpayment on it, that is not in the hands of the lender until the rest of the principal is paid off, it is a margin that is guaranteed to the lender in case of default, and has to be kept in escrow

also, just wanna say this: i keep seeing the word "principle" being used in relation to the amount owing in a bill

principle is more or less a synonym of axiom or rule or law, principal is the responsible party or the amount owed in a loan, or the chief executive of a school