But monetary policy is also injecting money into the economy. Both fiscal and monetary do this, but differ in two ways: the nature of the money injected and the way the injection is performed.

Monetary policy increases the money supply itself through the exchange of money for treasury bonds and relies on banks to distribute this "new" money, while fiscal policy redistributes money that already exists (previously collected through taxes) and gives it to active businesses through government purchases rather than to bond holding institutions.