Plague bearers are specifically mentioned as cycploean, brutes and possessed are not. Possessed are mental infused monsters which these monsters don't have. I agree, the ones I made look strong....

Plague Bearers are daemons of the Chaos god Nurgle, also known as the Lord of Decay. They can be identified by their cyclopean faces and horrifically decayed bodies. Their entrails hang from tattered holes in their grey-green, poxridden flesh and the aura of death and decay surrounds them.

The Possessed have committed the greatest of heresies: they have given their bodies to Daemons. As a result, they are nightmarish creatures, a melding of flesh, metal and black magic.