Assuming the product description is to be believed, then the only feature it lacks is true NKRO. I can't foresee any reason for anyone but a hardcore gamer of one of a couple of genres (FPS and rhythm games, mostly) will ever need anything closer to NKRO.
Of course, that does suggest that the circuitry and controller necessary to provide NKRO cost Diatec something on the order of $30 which strikes me as more than a little absurd. Since it is so absurd, it is also possible that this keyboard may be "lesser" in some other respects not mentioned in the product description. If you want to be absolutely sure, I'd shoot a message over to the owner of KeyboardCo through their own website.
I did check their website but couldn't find a similar product on offer there, so this appears to be an "Amazon-exclusive," so to speak. While I'm sure you could find it on sale on a Korean site like PCHome or ArmyGroup, I wouldn't trust the Google-Translated description there to give you a clear picture as to why this keyboard costs 20% less than its counterparts.