From Investopedia:
"Bills of exchange are similar to checks and promissory notes. They can be drawn by individuals or banks and are generally transferable by endorsements. The difference between a promissory note and a bill of exchange is that this product is transferable and can bind one party to pay a third party that was not involved in its creation. If these bills are issued by a bank, they can be referred to as bank drafts. If they are issued by individuals, they can be referred to as trade drafts."
Read more: http://www.investopedia.com/terms/b/billofexchange.asp#ixzz1tGHCLV7B