The non-threaded axle on your links left side is more the type race karts typically use. It requires separate rear wheel hubs that clamp around the axle and also uses a 1/4" key/keyways in the axle/hub to lock everything down. (although modern race karts typically usualy use 1-1/4" or even larger axle diamitor sizes.
The other 2 (threaded end) axles are just 2 diferent styles more typically used on fun or yard type karts. (they also use a 1/4" key/keyways, but lock the rim directly to the axle with a nut) This type of axle setup usualy cost less to buy everything than a race-kart type axle setup.
You can readily buy rims to fit directly on either of the threaded axles your link is selling, or 1" ID. race type wheel-hubs to adapt race-kart type rims to the non-threaded axle your link is selling.
It would end up costing more to buy everything, but If I was building a whole live axle go kart from scratch, I'd try to use a 1-1/4" diamiter race type (hollow) axle, and be using sprocket/wheel Hubs and Cassette type bearing componets like some of the ones you'll find for sale in these 2 links and pictured below on my kart:
http://www.bmikarts.com/shop/?cart=2007861&cat=259&
http://www.bmikarts.com/shop/?cart=2007861&cat=260
