Unclear Description: Exotic Eye Designs

Based on a quick scan, Technicolor Eyes seems to primarily cover unusual iris colors. I.e., they're using the typical meaning of "eye color" but with an unrealistically broad spectrum of colors. (The color also has to be unusual in-universe, not simply unrealistic design choices that are meant to be normal in-universe.)

Exotic Eye Designs explicitly does not cover mere unrealistic iris colors. The unusual element has to be either a strange shape (which obviously isn't covered by Technicolor Eyes), unusually colored scleras (i.e., the "whites" of the eyes aren't white), or color-changing irises.

So to me, the obvious distinction is that Technicolor Eyes covers unusual color choices for the common meaning of "eye color," i.e., iris color, while Exotic Eye Designs covers eye weirdness beyond iris color. It makes sense to me to have these as different tropes, since pushing the envelope of iris color seems common for trying to signal "special" or "exotic" characters without necessarily meaning they're something other than normal humans, while messing with pupil shape and/or non-white scleras generally crosses over into signaling something alien/supernatural/mutant, etc.

That being said, the Technicolor Eyes page does not explicitly say it means iris color (sticking to the ambiguous "eye color") and it blurs the line by using a page image that appears to include purplish-tinted scleras as well as red irises (it's not clear whether that is intended to be unnatural sclera color or an odd lighting effect). It also has some examples that cite unusual sclera colors, albeit usually in addition to weird iris colors which are clear examples of the trope.