What are the differences between complete dominance and codominance?

In complete dominance, the homozygous genotype results in the dominant phenotype, while the homozygous recessive genotype results in the expression of the recessive phenotype. The individuals with the heterozygous genotype in complete dominance can be referred to as carriers that are able to pass the recessive allele on to their offspring but won't actually express this gene themselves. This is because the recessive allele is masked. In the case of codominance, both alleles are expressed equally so both proteins are synthesized and appear to be expressed equally, depending on the traits.

complete dominance = "normal" expression of a single trait.

 Example: aa=produces only green and Aa or AA = both express the phenotype blue and therefore is dominant phenotype to aa

codominance= two traits are being expressed BUT you can see them both distinctly (you recognize them)

Only heterozygotes, both genes produce distinguishable product of both the two outputs
AA= produces blue and A+A+ produces red

Example: the heterozygote AA+ produces a spotted blue and red color

Incomplete dominance produces a new trait that is neither blue nor green, but a NEW color.

Example: say A+ A+ is a mutant gene (allele) and produces red, so
A+A+ or A+a = produces red, so aa is still recessive to A+A+

Now what if you have genotype A+A = this produces a new color: purple

In incomplete dominance, both colors are being expressed as a "blend" and it appears as a new color