Though the color on the headlight cover may be a little off, Fisher22 was right that there was a difference between the gloss of the bumper and the headlight cover which may explain the difference in appearance between the two.
So I polished the left cover even more and under incandescent and LED garage light got these results . . .
Polished Left headlight cover (on the right) with unpolished Right headlight cover (on the left)
In this light the color difference isn’t quite as noticeable
One thing for sure, a black or white car would be easier to color match.