What is the difference between Roast Beef and Prime Rib?

Roast beef is just a generic name for a cut of beef that’s baked (roasted) in the oven.

Prime rib is roast beef, but a specific cut of beef that generally refers to a Rib Roast, also known as a Standing Rib Roast. Technically, it’s a rib roast using USDA Prime meat, but most restaurants do not use USDA Prime.