Red fel and green fel

So, I'm a little confused. My main is Destro Warlock. The color of Fel is green. Warlocks use fire and, after a special quest, can color their fire spells green, color of fel. Felfire is stronger than normal, elemental fire. Destro's fel fire rain is stronger than normal fire rain (I mean, in lore). But at the same time, red is also a color, showing that there is too much Fel. Red Orcs are the next stage of Fel corruption after Green Orcs. The red skin of the Felblood elves is the next stage after the green eyes.

Abyssals, the more powerful infernals, are almost always red, and infernals are almost always green (with very rare exceptions). Sargeras is red. Gul'dan in his final stage first burns with green fire and then red. Aggramar is red in raid. I would have thought that the red flame was an enhancement by Sargeras himself, but the red orcs and elves say otherwise.

I may be overthinking this, but does anyone else find it odd that the fire turns red/orange again after being overpowered by too much Fel? I mean, we don't see a visual difference between elemental fire and "hell" fire. It's just Red=>Green=>Red Again

Thoughts?