I was watching a cooking show the other night and it was an episode on
standing prime rib roast. And when the host of the show requested the
butcher to pick out a nice piece for him, the butcher happen to
mention that getting the rib roast from the loin end is better since
it contained less connective tissue and the meat is more tender.

So, I went to the supermarket today after work, when the butchers or
the meat processors as they're called happen to be off for the day
already, and had no idea how to distinguish the rib roast that's from
the loin end and the ones that are not.

The only differences I noticed between the different standing prime
rib roasts were that some contained noticeably shorter ribs and the
others contained longer ribs.

I was trying to rationalize that since the loin end is where the
"lower" part of the rib cage would be, the rib roast packages with the
longer rib bones must be the ones that come from the loin end. But
just wasn't sure and there were no butchers to be found, so I decided
to pose the question in here to confirm before I shell out over $50
for a nice chunk of roast.

First of all, is there truth to the claim that the rib roast from the
loin end contains less connective tissue and would have more tneder
meat than the roast from the other end?

As well, how can I tell for sure, given a set of packages of rib
roasts, which ones are from the loin end and the others are not?
Thanks for your time and courtesy!