outofcombat.png
When out of ocmbat, nameplates has a reduced size.
It's configurable.
friendlyplayer.png
If friendly nameplate are enabled, this is how Plater show plates for friendly players.
incombat.png
When in combat, plates has normal size (also configurable).
As DPS the red bar means the mob has aggro on you.
If you are a tank, would be opposite: red nameplate = no aggro.
AS DPS the purple color means the mob isn't attacking you.<...