The Boston Globe writes on "Money market funds vs. money market accounts", asking "What is the difference between a money market mutual fund and a money market deposit account?" The answer: "Good question! As investors continue to move money into more conservative holdings such as cash and cash equivalent investments, it is important to understand the difference between a money market mutual fund (sometimes known as a money market fund or a money fund) and a money market deposit account. Money market funds and money market deposit accounts are similar in that they both usually invest in short-term, fixed income investments such as U.S. Treasuries. [This is incorrect; money funds do, but MMDAs are a promise to pay by the bank. -Crane] By definition, short-term, fixed income investments are those with maturities of less than one year.... Both types of investments offer a high level of flexibility and liquidity as you can often write checks against these accounts and make ATM withdrawals from them."
