You Do Need power plug adapter while traveling from French Guiana to Saudi Arabia.

Here is Why You Need An Adapter

The outlet and plug type used in Saudi Arabia 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

Saudi Arabia

In Saudi Arabia, outlets of type G are in use.

Type G