You Do Need power plug adapter while traveling from Belgium 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 Belgium are C and E. This is how they look like.

Belgium

In Belgium, 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