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

Here is Why You Need An Adapter

The outlet and plug type used in Israel are C and H 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

Israel

In Israel, outlets of type C and H are in use.

Type C

Type H