What's the difference between a pulmonary embolus and a pulmonary infarct?

Cause and effect: An embolus is something that can float through blood and then plugs the flow. It's usually a blood clot or air. A pulmonary infarct occurs when the embolus goes to a pulmonary artery and the lung down stream dies from lack of oxygen.

They're related: A pulmonary embolism is a clot that has lodged in a pulmonary artery as a complication of thrombophlebitis elsewhere, usually the legs. If all blood supply to a certain area of the lung is shut off by a blood clot, the lung can be severely damaged and die from lack of oxygen. This is called an infarction. It isn't common because the lungs have a dual blood supply.