What is the difference between pleural effusion and pulmonary embolism?

A pleural effusion is a build up of fluid between the (visceral and parietal) layers which line the lungs and chest cavity.

Whereas.......

A pulmonary embolus is a sudden blockage in a lung artery caused by a blood clot that travels to the lung from another part of the body.

NB:

- Pleural effusion = problem in visceral and parietal layers

- Pulmonary embolus = problem in lung artery