GR vs. SE: The crossover parts are further upgraded and cryogenically treated.
The compression driver (tweeter) diaphragm and surround is updated to a
new material (should have better extension up top). The woofer cone material
has gone from all paper fibers to a blend of synthetic and paper fibers.
Supposedly these upgrades are trickle-down from the Kingdom Royal project.
Finally, the fit & finish is higher quality.
Sonically, I have no first-hand experience here. A while ago I read another
guy's brief SE vs. GR comparative account on another forum -- he said that
the Canterbury GR sounded more "open" than the SE; he clearly
preferred the GR and bought them. I forget whether this was the same guy
that quickly upgraded to Westminster GR, which of course he reported as
more MOAR better :)
Personally, I'd much rather have a Westminster (GR or SE) than the Kingdom
Royal.