Ok let me start with the definitions of incomplete dominance and codominance.
incomplete dominance - The situation in which the phenotype of heterozygotes is intermediate between the phenotypes of individuals homozygous for either allele.
codominance - The situation in which the phenotypes of both alleles are exhibited in the heterozygote because both alleles affect the phenotype in separate, distinguishable ways.
It is the standard textbook example of incomplete dominance to show a cross of red and white Snapdragons of pure bread. Which yields the phenotypic ratio of 1 red : 2 pink : 1 white. The standard text example of codominance is AB blood type where the A glycoprotein and B glycoprotein together produce a distinguishable phenotype apart from AA or BB.
I really don't understand the distinction between intermediate phenotypes and distinguished phenotypes. How is pink not distinguished from white and red. Consider a hypothetical example of some insect that interprets red, white and pink as distinguishable signals where perhaps red is a safe flower, white is ignored, and pink is dangerous. Say these signal recognitions have evolved based on the insects contrast against the flower pigment and the probability of being eaten by a predator because of increased exposure while getting nectar from the flower. I suppose I have a misunderstanding but wouldn't the red, white, and pink phenotypes be distinguishable rather than intermediates in that case?
So I'm probably just being an idiot but how is incomplete dominance different from codominance?