Not sure if you're asking about handle thickness or blade stock, but the stone washed blades look a tad bit thicker even though I'm sure they're the same, it's the rounded spine on the coated blade that makes it look thinner. I've noticed this same optical illusion on my own knives.
But if we're talking about the handles, looks like the brown handles are tad bit thicker. Something about the rads on each one making them appear to be different.
Is this the GSP?