You Do Need power plug adapter while traveling from Brunei to Myanmar (Burma).

Here is Why You Need An Adapter

The outlet and plug type used in Myanmar (Burma) are A, C, D, G and I and in Brunei is G. This is how they look like.

Brunei

In Brunei, outlets of type G are in use.

Type G

Myanmar (Burma)

In Myanmar (Burma), outlets of type A, C, D, G and I are in use.

Type A

Type C

Type D

Type G

Type I