I am aware enemies can be green, yellow and red named. However, I have seen a few that appear to have orange, rather than red names. They really do seem tougher than the yellows and less tough than the reds. Am I imagining things, or are there really orange-named enemies? Also, what is the criteria for assigning a name color to a particular enemy? Is it the number of that enemy the payer has killed? Isit the player's adventuring level?
https://www.shroudoftheavatar.com/playerinstructions/ under Combat: Nameplate Colors and Creature Strength yes, the enemy color tiers are based on the difference between your level and the mob's.
It may be worth noting that night vision can alter the colors somewhat. For me, using night vision makes a green nameplate look blue
