Difference between standing rib roast and prime rib? Both look identical.

The meat will taste better with the rib attached roast. You can cut the meat away from the bone and tie back on with butcher string. Cook with bone on top to let juices flow down into meat.
Remember to pull out 5F lower as the roast will still cook while resting. Save bones for lunch the next day with BBQ sauce.

The cut is standing rib roast or rib roast. Prime is the grade of beef. So a roast is technically only "prime rib" if it is prime beef. This is almost always used incorrectly.

Standing Rib Roast is with the bones attached; prime rib the bones have been removed.

I think they are the same. I think anyway. :)