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

Greenland

In Greenland, outlets of type C, E, F and K are in use.

Type C

Type E

Type F

Type K

French Guiana

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

Type C

Type D

Type E