You Do Need power plug adapter while traveling from French Guiana to Western Sahara.

Here is Why You Need An Adapter

The outlet and plug type used in Western Sahara are C and E and in French Guiana are C, D and E. This is how they look like.

French Guiana

In French Guiana, outlets of type C, D and E are in use.

Type C

Type D

Type E

Western Sahara

In Western Sahara, outlets of type C and E are in use.

Type C

Type E