What is Difference between pulmonary and fat embolism?

Pulmonary embolism (PE) is a blockage of the main artery of the lung or one of its branches by a substance that has travelled from elsewhere in the body through the bloodstream (embolism). Usually this is due to embolism of a thrombus (blood clot) from the deep veins in the legs, a process termed venous thromboembolism. A small proportion is due to the embolization of air, fat or amniotic fluid. The obstruction of the blood flow through the lungs and the resultant pressure on the right ventricle of the heart leads to the symptoms and signs of PE. The risk of PE is increased in various situations, such as cancer and prolonged bed rest.[1]
Symptoms of pulmonary embolism include difficulty breathing, chest pain on inspiration, and palpitations. Clinical signs include low blood oxygen saturation and cyanosis, rapid breathing, and a rapid heart rate. Severe cases of PE can lead to collapse, abnormally low blood pressure, and sudden death.[1]

Pulmonary emboli develop by a wandering blood clot (usually from the legs), which travel to the lungs via the heart. Several of these clots could migrate to the pulmonary vasculature and aggregate in one vessel.

A fat embolism is a large fat droplet that enters the bloodstream. A fat embolism occurs most commonly following a fracture of the pelvis, femur, or tibia. Multiple fractures are more likely to lead to fat embolism than single fractures. Symptoms of fat embolism usually begin 12 to 72 hours following the injury. Symptoms of fat embolism occur when the small fat droplets obstruct the small vessels in the lung or brain. The obstruction reduces the blood flow to parts of the lung or brain, causing those areas to malfunction.

What are the symptoms of a fat embolism?
Symptoms of a fat embolism may include rapid pulse, shortness of breath, rash, agitation, lethargy, confusion, seizures, and coma.

How does one treat a fat embolism?
Treatment for a fat embolism is supportive and includes supplemental oxygen, hydration, and in more extreme cases mechanical ventilation. Surgery may be required in some cases.