One is a grade of beef and the other is a breed. USDA Prime is a marbling grade on the cut of meat itself. This marbling is the fat in between the muscles which adds tenderness and flavor to the meat. Only 3% of all meat in the USA is graded as USDA Prime! Black Angus is a breed of cattle different than your commodity breed. It has a more beefy flavor and Angus cows are typically more fatty adding more flavor to the meat! So it is completely normal to find USDA Prime Black Angus beef which we have!