While both of these are liabilities, Notes Payable involves a written promissory note. For example, if your company wishes to borrow $100,000 from its bank, the bank will require company officers to sign a formal loan agreement before the bank provides the money. (The bank might also require your company to pledge collateral and for the company owners to personally guarantee the loan.) Perhaps the loan paperwork will be a half inch high. Your company will record this loan in its general ledger account, Notes Payable. (The bank will record the loan in its general ledger account Notes Receivable.)
Contrast the bank loan with phoning one of your company’s suppliers and asking for a delivery of products or supplies. On the next day the products arrive and you sign the delivery receipt. A few days later your company receives an invoice from the supplier and it states that the payment for the products is due in 30 days. This transaction did not involve a promissory note. As a result, this transaction is recorded in your company’s general ledger account Accounts Payable. The supplier will record the transaction with a debit to its asset account Accounts Receivable (and a credit to its account Sales).