What is the difference between prime rib, rib eye roast and standing rib roast?

Pretty much all the same.

Prime rib should be a Prime grade standing rib roast without the rib bones.

Rib eye roast should be cut slightly different and the ends should look like a ribeye. This is the chunk of meat the butcher cuts ribeye steaks off of.

Standing rib roast has the rib bones left intact, with or without the backbone attached.

Thank you.
Check this out.

http://www.txbeef.org/cuts_detail.php3?this_section=Rib...etail_page=Rib+Roast

Yep. All pretty much the same. I like the middle cut, I think it is the bottom pic.

Prime rib frequently refers to the cooked product, regardless of grade. Just because you order prime rib from a restaurant doesn't mean it's USDA prime--more likely it's choice. So after cooking it, you can call it prime rib.

At the store you'll find:
Rib roast: typicaly boneless
Standing rib roast: typlically with the bones attached (whether pre-trimmed and tied back on or left intact).
Ribeye roast: another name for one of the above.

You can get more specific, as to the smaller and larger end, which numbered rib bones are included in the cut, etc. But just look for a rib roast, bone in or out is your choice, that is the size you want and that has the most marbeling.

Bone-in roasts don't need a rack to cook since the bones serve this function.
Boned roasts benefit from being cooked on a rack.

Then just cook and wow family and friends!!