Prime rib is a beef roast that comes from the rib section of the cow. It is essentially a large ribeye roast, usually cooked as a whole roast rather than individual steaks.
Basic cut type
Prime rib is cut from the beef rib primal, specifically ribs 6 through 12 of the animal.
When sliced into individual steaks instead of roasted whole, the same section of meat is sold as ribeye steaks.
Bone-in vs boneless
Prime rib can be sold bone-in (often called a standing rib roast) or boneless, where the rib bones are removed to create a ribeye roast.
Both versions are the same fundamental cut; the bone-in version is often chosen for flavor and presentation, while boneless is easier to carve.
First cut vs second cut
Within the rib section, the leaner “first cut” or “loin end” comes from the ribs closer to the loin and tends to be more tender with a larger central eye of meat.
The “second cut” or “chuck end” comes from the ribs closer to the shoulder and has more fat and marbling, giving it a richer, beefier flavor.