You Do Need power plug adapter while traveling from Vietnam to Azores.

Here is Why You Need An Adapter

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

Vietnam

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

Type A

Type B

Type C

Azores

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

Type B

Type C

Type F