Race v Ethnicity

My interest in genealogy and recent DNA testing lead me to an interesting question: what is the difference between race and ethnicity? I have come to think of myself as of the Caucasian race and most likely Welsh / English / German in ethnicity--although, as an 11th generation American, some of the European connections are stretched.

At some point, ethnicity--and even race--will be a matter of personal preference instead of appearance. And then at some later point, these distinctions will not matter much at all.

Here is a good Race v Ethnicity Comparison Chart. Do you see anything missing?