You Do Need power plug adapter while traveling from Rwanda to Guinea.

Here is Why You Need An Adapter

The outlet and plug type used in Guinea are C, F and K and in Rwanda are C, E, F and G. This is how they look like.

Rwanda

In Rwanda, outlets of type C, E, F and G are in use.

Type C

Type E

Type F

Type G

Guinea

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

Type C

Type F

Type K