What's the difference between yellow eyes and orange eyes?

[Bumja]

Xehanort, Terranort, Braig (end of the game), Xigbar, and Saix all have Yellow eyes.
Ansem SoD, Xemnas, and Ansem the Wise all have Orange eyes.
(Look up what eye color that they have, its correct. I dont have the patience to post everyones eye color.)

Im guessing theres something symbolic on the eye color since Briag's and Terra's change color.

On a side note, Lea's and Isa's eye color change as well.
http://www.risingstarforums.net/random/1261587329214.jpg

Notice how Lea's eyes are Turquoise (Like Larxene and Riku) and Isa's are Blue?

Then when they become nobodies, Axels eyes are Dark Green, and Saix's are Yellow.

Any theories and explanations?

 

[impart]

yellow = evil
blue= good
green= in between

 

[Bumja]

Orange?

And by the way, Xaldin's, Laxaeus's, and Marluxia's eyes are blue as well.

 

[Gram]

Any theories and explanations?

they use contact lenses!

 

[impart]

Orange and yellow both = evil

look at other games made by Nomura.
his protagonists have blue eyes
his antagonists have yellow/orange
as for Xaldin, Laxaeus, and Marluxia- nobody knows

 

[KeyofEvil'sBane]

I think the orange we see in Ansem SOD and Xemnas is meant to mean the same thing as the yellow eyes of current villians, but the color changed to yellow due to simple design changes.
Also, any change in eye color is generally the result of some kind of affiliation with darkness (ex. Braig, Lea, Isa)

 

[HeartSeams]

Orange?

And by the way, Xaldin's, Laxaeus's, and Marluxia's eyes are blue as well.

I'm pretty sure Xaldin actually has purple eyes...

Yellow Eyes and Pointed Ears means the character has some relation to Xehanort, according to Nomura. This is why we see Braig with brown eyes and rounded ears early in the game, and then when he shows up in the end he has the gold and pointed ones.
So, I supposed that means, Saix might have some relation to Xehanort in-between BBS and KH1.

Orange is probably just an aesthetic change that means the same as yellow.

People used to think if your eyes were yellow/orange then you had gotten too close to the darkness, but, I couldn't find a Nomura quote where he said this, so, it might have just been fan speculation.

 

[Zulkir]

↑
correct

The Yellow=Darkness isn't actually proven, just fan speculation)


Xehanort(before his merger with Terra) ALWAYS had Yellow eyes. Even the render of young Xehanort shows yellow eyes.


Yellow eyes=Xehanort/connection with Xehanort

Orange eyes=Orange eyes, Ansem has them even before he finds Xehanort.

Eye color has no affiliation with darkness/light, there are those who had a LOT of dark energy (Riku, Terra) and still had blue eyes. Terra got so angry that a massive explosion of darkness surrounded him and he still had blue eyes.

No amount of darkness will turn your eyes yellow, it requires a voluntary, mutual connection with Xehanort(or being possessed) AFAIK(Saix who fully embraced the aspect of being a Nobody, no longer regarding Lea/Axel as a friend, Braig who wanted a keyblade from MX.)