A rift valley is a linear-shaped lowland between several highlands or mountain ranges created by the action of a geologic rift or fault.
Ex.) East African Rift
Ex.) East African Rift
A mid-ocean ridge is a general term for an underwater mountain system that consists of various mountain ranges, typically having a valley known as a rift running along its spine, formed by plate tectonics.
Ex.) The Mid Atlantic Ridge
East Pacific Rise
Central Indian Ridge
Juan de Fuca Ridge
Ex.) The Mid Atlantic Ridge
East Pacific Rise
Central Indian Ridge
Juan de Fuca Ridge