Steel and handle. KS4020X uses 8Cr13MoV with a titanium coating and a black G10 handle. KS4020MCG uses D2 tool steel with a BlackWash finish and an OD green Micarta handle. Both are 4.25 inches closed with a 3.25 inch blade and an extended tang.
8Cr13MoV is the value benchmark: good corrosion resistance, fair edge retention, sharpens on anything. D2 holds an edge considerably longer and is semi-stainless rather than stainless, so it wants wiping after wet work.
If you are choosing between these two on performance, this is the difference that matters.
Black G10 is harder, more textured and completely stable. OD green Micarta is warmer in the hand, gains grip as it wears, and darkens with use.
Neither is more durable in any way that matters; it is a preference.
Both currently sit in our Closeouts category, which means new stock at a clearance price with finite availability. When they go, they generally do not come back.
Kershaw's Limited Lifetime Warranty covers the original owner and is non-transferable. See the Kershaw warranty.
Specifications above come from the manufacturer. Live prices and availability are in the strip below, pulled from the catalog at build time rather than typed into the copy, so they cannot go stale on this page.