Here's why:

* Mountains are defined as having a significant elevation above the surrounding land, often with a peak and steep slopes. They typically rise at least 1,000 feet (305 meters) above the surrounding area.

* Hills are also elevated landforms, but they are generally lower and more rounded than mountains. They are typically less than 1,000 feet (305 meters) high.

So, while both mountains and hills are higher than the surrounding land, mountains rise much higher and more dramatically.