Here are some differences between Loake and Church's (similar models).
It's mostly a question of materials and finishing, I think:
Loake uppers are thinner, less even-grained (so they crease unevenly) and drier/stiffer-looking, and the colour is not so deep or rich as on Church's. The stitching is finer and more carefully done on Church's. Loake soles are a little stiffer and less comfortable to walk in. Church's heels are dense and make a very nice "leathery" sound when walking versus Loake's drier sound. Church's lining is superior - silky to the touch against Loake's smooth but slightly "plasticky" feel. Church's seem to breathe a bit better - they are certainly much, much more comfortable in hot weather. New Church's smell strongly of leather: new Loakes smell of leather too, but also of chemicals - glue, plasticizers maybe. Church's shoes are a bit heavier overall, more substantial. Having a lot of dress shoes I've never worn a pair enough to wear them out, so I can't compare ultimate durability. Comfort and appearance are my priorities. I'll see if I can manage some pics.