I noticed the same thing and the dealer explained that the residential refrigerator came with extra battery and the inventor and accounted for most the weight but he could explain why so much of it went toward pin weight.
There are some other difference also. Tank sizes are different between the two models when you check the website. The dealer said that was error on the website but who knows.
Also, on the one we are looking at the front cap has window and the TV goes up and down and the ones in most pictures show sold cap and no window.
I will know next week since I bought it and we will hit the scales on the way home.
This is the one with the front window and understand they are kinda rare...
Front Window