I dont know about other places, but there is no fit and finish difference that i can see. The cost differences are generally a function of white steel being easier to forge, grind, and sharpen. Other places may ask for different things or order differently, so i cant speak to that. But for us, there are no differences in the rounding of the spine and choil or anything like that. There are aesthetic differences in terms of kurouchi vs migaki, and, of course, the steel types. The steel types also dictate thinness to a degree. The white steel, being easier to forge, tends to be thinner (as is the case with many craftsmen... easier to forge and grind steels can more easily be made thinner).