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

Here is Why You Need An Adapter

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

Brazil

In Brazil, outlets of type C and N are in use.

Type C

Type N

Belize

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

Type A

Type B

Type G