There is no difference. Just Rift Valley is shorter to say>
The Great Rift Valley is in Eastern Africa It surrounds lake Victoria
Rift valleys appear at divergent tectonic plate boundaries. It is thought to be a process of inner earth heat
Rift valleys occur when continental plates are pulling apart from one another, for example the East African Rift Valley.
A rift valley is formed by the depression of a block of the earth's crust between two faults or groups of faults, of approximately parallel orientation.