Compression and extension forces both can build mountains from plates either pushing together or pulling apart.

Does compression form mountains?

Compression forces can cause mountains to form or earthquakes to occur depending on how the Earth's crust reacts to the force. When the Earth's crust is pushed together via compression forces, it can experience geological processes called folding and faulting.

What type of forces create mountains?

Compression forces form folded mountains, and tension forms fault- block mountains. Differences in forces, rather than in rock type or duration of the forces, cause formation of these two types of mountains.