Yellow vs white corn is controlled by a single gene with two alleles:
_Y_ (dominant) for yellow endosperm and _y_ (recessive) for white
endosperm (lack of carotenoids in that tissue). There may be a
nutritional difference favoring yellow corn for animal feed on the
count of pro-vitamin A.
Corn selected for high oil which is multi-genic in nature has little or
nothing to do with yellow-vs-white.
Milling properties of the endosperm is probably complex also...and not
likely to be the direct result of yellow vs white.
Of our domesticated plants, corn has perhaps the greatest genetic
variability allowing the "shaping" by breeding of almost any trait
of the plant and its kernels.
-- Steve Modena ab4el@Cybernetics.NET