the weight difference is in the barrel the standard carbine comes with a 16.1 inch round barrel 4.5 lbs the small game carbine with skinner sight comes with a 17 inch Octagon barrel 5.75 lbs

Sounds like you answered your own question. ??? The one with skinner sights weight 1 more pound ???
Not really sure what you are asking, both have the same sights. The one you linked to (17" barrel) is 5.75 lbs and the other one ha a 20" barrel and is 6.5 lbs.
If one has a plain sight and the other a skinner, then they are not the same gun. Without a model number, the other answers cannot be accurate.

Hi kenneth and welcome. It is the "Octagonal 17-inch Barrel" that adds the additional weight to the model over the 16.1- inch round barrel model. Cheers, stay safe and enjoy!