You Do Need power plug adapter while traveling from Haiti 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 Haiti are A and B. This is how they look like.

Haiti

In Haiti, outlets of type A and B are in use.

Type A

Type B

French Guiana

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

Type C

Type D

Type E