The climbing form of 'Devoniensis' is identical to the shrub in all but vigour and habit, so it sounds as though there might be more than one rose going under the name 'Devoniensis'. That said, it's worth keeping an eye on the suspect rose for a few years. Leaving aside the blooms, how does it compare, feature by feature, with the climbing form?

The blooms of 'Devoniensis' do vary in fullness from season to season, but both shrub and climber have blooms that go through the same range of form and colour, and they have the same leaves and purplish-red new growth and glandular pedicels. The portrait in Henry Curtis' 'Beauties of the Rose' is a pretty good likeness and captures the posture of the buds very well.
Right from the start, the climber has impressive prickles that are - as Patricia noted - so hard to dislodge they seem to be welded to the stems. For us, the shrub had less prickles when young but as the plant aged it became pricklier.

I've found the shrub form to be very slow to establish. The plant in our garden grew so slowly for its first eight years that I worried about its constitution. In its early years it made a sparse, awkward plant, barely 3' (approx 1 metre) high and didn't put much new wood on each year. It was definitely the runt of the Teas here. Despite that, it still produced intermittent crops of gorgeous blooms from that scrawny frame.
After its eighth year it seemed to change gear and began to grow much more strongly and now it takes conscientious picking and trimming to keep it to reasonable bounds. It's one of the healthiest roses in the garden and repeats its bloom so quickly that it's rarely without a crop of buds and flowers.

Impressively large old Devoniensis 'trees' (like the one in Jeri's picture) are seen in old gardens and cemeteries and there's been some speculation re whether they can possibly be the shrub form or whether the forms in commerce have lost vigour. Watching our shrub over 15 years, I don't think it's a case of diminishing vigour - just that the shrub form of 'Devoniensis' has an especially long childhood and adolescence and if you're prepared to wait for a decade (in the right climate), the mature shrub is really something special.

2 photos attached - all blooms are from the same plant - shrub form of Devoniensis.

I am only now seeing your pertinent question now about whether all plants of 'Devoniensis' are the same worldwide. There was some discussion on the Antique Roses forum about 4-5 years ago about this question, and I don't know if anything was decided for certain, but it does seem possible that there may be two different roses being sold in the U.S. as 'Devoniensis'.

I don't think it's possible to read the entire thread without being a Houzz member (which I no longer am), but parts are visible: https://www.houzz.com/discussions/1568872/why-is-devoniensis-not-more-popular

Both roses have similarly colored flowers (cream with yellow and pink shadings), dark green foliage, and reddish/ purplish canes/ new growth. One rose has larger leaflets, and looks more tea-like, and the other has smaller, glossier leaflets, and seemed HT-like. I believe that they are both very fragrant.

I doubt anything was proven decisively, and i is possible that there is only one clone that grows differently in different conditions. Even if there are two different roses, I'm guessing they have enough in common that someone could grow both, and not think to compare them closely.

If there really are two different 'Devoniensis' roses being sold in the U.S., I wonder if that error could have occurred in other countries also via imports from North America or independently. Devoniensis was introduced almost 200 years ago, so that's plenty of time for more than one "confused in commerce" situation.

Virginia