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

Here is Why You Need An Adapter

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

Belize

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

Type A

Type B

Type G

Guinea

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

Type C

Type F

Type K