What are the visible differences between Goodyear and Blake shoe construction?
Why, yes. Yes, there are. Here's a picture from the La Botte Chantilly website
showing how Blake construction works:
As you can see, the stitching that attaches the upper to the insole to the sole is on the inside
of the shoe. This means that you should be able to see or feel a row of stitching along the perimeter of the inside of a Blake-constructed shoe. On a Goodyear-welted shoe, there is no interior stitching. The upper is attached to the insole via stitching through the insole, the upper, and a welt strip; and the welt strip is then stitched to the outsole: