Being a Hereford guy, I thought all Angus cattle were "Aberdeen" Angus. 

So I looked it up and found this.

Very interesting. A quote from this link:

"Modern Angus cattle are significantly different from their Aberdeen Angus ancestors. Today’s Angus is a larger animal (up to 1,000 pounds dressed) with more mass in the chuck and round primals, longer legs, and a digestive system adapted for a grain-finishing diet. Many traits of domestic breeds have been crossed into the Angus bloodline to improve feedlot efficiency and increase red meat yield. Surprisingly, some major branded “Angus” beef programs don’t even require cattle in the program to be of Angus lineage; they only need to exhibit traits typical of Angus, such as a black hide and no shoulder hump." [emphasis mine]