You Do Need power plug adapter while traveling from French Guiana to Falkland Islands.

Here is Why You Need An Adapter

The outlet and plug type used in Falkland Islands is G 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

Falkland Islands

In Falkland Islands, outlets of type G are in use.

Type G