A bill of sale is more akin to a receipt rather than a contract. Since it is such a simple document, there is no way to truly enforce it. If the bill of sale is the only document you use in a transaction, it is best to ensure there is enough detail on it to make the transaction enforceable.
A contract for deed, also known as an installment sales contract or installment land contract, is a legal agreement where a buyer makes regular payments to the seller for the property over time.
An installment sale has the following primary disadvantages: The sold assets will not receive stepped-up basis in the event of your death.