How are porpoises different from dolphins? (The 3 F’s)

Dolphins and porpoises can be easily confused at a glance. They are both small cetaceans and extremely intelligent. Each also have complex brains with a forehead called a melon. Using their melon, they can easily navigate using sonar (sound waves). However, you can use the 3 F's (Face, Fin, and Figure) to help you visually tell the difference.