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

Here is Why You Need An Adapter

The outlet and plug type used in Equatorial Guinea 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

Equatorial Guinea

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

Type C

Type E