Here's a breakdown:
* Government bond: This is the most common term for a government IOU. It's a debt security issued by a government to raise money. Investors buy these bonds, lending money to the government in exchange for a promise of future interest payments and repayment of the principal at maturity.
* Treasury security: This is a specific term used in the United States for government bonds issued by the U.S. Treasury.
* Government note: This term is sometimes used interchangeably with bond, but it typically refers to shorter-term debt securities, usually with a maturity of less than 10 years.
* Government bill: This term refers to short-term debt securities with a maturity of less than a year.
In general, the term "government IOU" is a less formal way of referring to these debt instruments, while "government bond" is the most widely used and accepted term.