Where they differ is how they’re cooked – which is because of their size.
- Prime rib is a roast.
- Ribeye is a steak.
The former is slow cooked and the latter can be seared hot and fast – both methods create different flavors.
Prime rib is also far more meat and will always cost more.
They’re the Same Cut of Meat and Come From the Same Place on a Cow
A ribeye steak is typically 0.75 – 2 inches thick and can be bone-in or boneless.
A whole bone-in prime rib is the width of seven ribeyes and weighs anywhere from 14 to 22 lbs.
In terms of taste, you won’t find significant differences as they’re from the same part of a cow.
It’s called the “rib primal.”
BUT Anatomy Can Matter When Talking About BOTH Cuts
As you go from front to back on a cow – various muscles can be minimized and maximized.
There are 3 major muscles that make up a ribeye steak.
- Longissimus Dorsi – the “Eye”
- Spinalis Dorsi – the “Cap”
- Complexus
These muscles are held together by a tender sinew membrane and large swaths of fat.
A whole 7-bone roast (ribs 6-12) is a lot of meat and costs A LOT.
Due to this, Butchers will cut 2 roasts called either:
- 1st Cut
- 2nd Cut
- First cut prime rib: Ribs 10 – 12; Contains a large “eye” but smaller ribeye cap. Contains no complexus.
- Second cut prime rib: Consists of ribs 6 – 8; Less uniform, contains more connective tissues, but more fat (flavor). Has a smaller eye but bigger cap.
For steak, you generally want meat from ribs 6-8 because you get more Ribeye cap – which is one of the best cuts on the whole cow.
BUT for something like prime rib, you want meat from 10-12 because the Eye is bigger.
Hence 1st and 2nd cut.
A Quick Rundown of Stereotypical Cooking Methods
Prime rib is either:
- Slow roasted first and then broiled or seared 2nd.
- Seared or broiled first and then slow roasted 2nd.
Either method works and can result in even doneness across the entire roast.
Ribeye steak is typically just seared over high heat because it’s thin.
BUT it can similarly be “reverse seared” to control internal temperature better.
