You Do Need power plug adapter while traveling from Equatorial Guinea to French Guiana.

Here is Why You Need An Adapter

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

Equatorial Guinea

In Equatorial Guinea, outlets of type C and E are in use.

Type C

Type E

French Guiana

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

Type C

Type D

Type E