[rlh1957]

Manf change the line over mid year to adjust for an refrigerator model that could be better supplied or change material patterns. It doesn’t make one better or worse than the other, but subtle changes will change weight, sometimes cost.
If you’ve got a manf line going and 40 gal grey tanks are hard to get you may phase it out and go with a 35 gallon tank or a 50 if space and costs allow it.
One model may have a dinette/sleeper or a table & chairs. Maybe a different cabinet/drawer layout.

I would look for the tow weight you need and floor plan that works for you.
Wish us most important was floor plan that worked for us, then working around that we made sure the weight and length was what we wanted. With a F350 we were sure weight wouldn’t be a factor wanting to be in under 35ft.
That is why we say look at the sticker on each truck or towed rig and not depend on the published brochure specs. Every tow vehicle and every towed rig can have different specs… so very different than published specs.