You Do Need power plug adapter while traveling from Gambia to Liberia.

Here is Why You Need An Adapter

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

Gambia

In Gambia, outlets of type G are in use.

Type G

Liberia

In Liberia, outlets of type A, B, C and F are in use.

Type A

Type B

Type C

Type F