Of course I cannot see a thing ..

Generically a rear hub tends to use 1/4" balls a front smaller ones like say 3/16. 5/32" the cones differ as a result + the axle diameter.

I found the 'Wheels'for Campagnolo to last longer than Tulio's Originals .. perhaps the old Italians tempered them too hard .

the Upstart Colorado company left a little ductility in the temper.