The answer depends on context. Generally, in an SAP scenario, “payment methods” refers to how funds are transferred. In that case, the four most common payment methods in SAP are eCheck, ACH transfer, credit card, and debit card.
Outside of this context, “payment method” may also refer to options and terms related to when a customer can pay (or must pay). In that case, “payment methods” include milestone/periodic billing, payment guarantees, pre-payments (including partial down payments), and “payment on account.” In this last case, the full amount of the transaction is added to the customer’s accounts receivable balance for payment at a later date.