The 4200 vs. bedroom is only a couple of inches shorter than the 4100, but nothing that is actually noticeable in the unit (especially with the HUGE picture window, which in my opinion actually makes the 4200 look bigger). As far as the Bathrooms go the 4100 is by far the winner with the dual doors and a lot more space and storage. In the living area the 4200 is the clear winner when inside it. The 4200 seams much larger when inside it, because it does not have the center island sticking into the living space (both floor plans are maxed out at 429 sq. ft.). In the Kitchen (in my opinion) the 4200 is the winner with about the same counter top space, the 4200 has ALOT more storage, pull out trash can, raised island for barstools, pantry, and the option for the residential 23 cu ft. refrigerator that comes with 1000W inverter and two 6V deep cycle battery's, the mini fridge for the patio is also excess able from the kitchen so it can also be used for more kitchen refrigeration (which is over doubles that of the 4100). The garage area's the 4100 has more un-obstructed space however in the 4200 we managed to leave enough space between the 2nd bathroom wall and the out side wall to fit a side X side or golf cart. The 4200 definitely has the better 2nd bath with the industry's first 2nd full bath, IPO the 1/2 bath that comes in the 4100. The side patio is all bonus space on the 4200 (above and beyond the 429 sq. ft. of living space), the wall inside the patio is actually an exterior wall, so you can leave your side patio down even in wet conditions. If you choose to leave your camp site all you need to do is lock the sliding glass door on the side and not worry about having to close it up every time you leave. The patio area also has a 40" flat screen tv, out side refrigerator, and the TV baggage door comes down to act as a small table top, the garage DVD player goes to the TV and exterior speakers, and there is a ton of LED lighting including inside the huge 20' awning above. A lot of people think they cant get into camp sites with the side patio, but it actually takes up less space than the awning does on the side. The nice thing about the patio built into the living space it brings interaction between the outside and inside camping experience. I know when we go camping typically your either inside or outside with no interaction between the two, the side patio with big sliding glass door changes all that. The other benefit is that you are also not tracking in dirt and grass into your unit because the patio is on an elevated plat form. However if you choose not to use your patio and leave up it does not affect the floor plan at all, and still gives you one of the best floor plans in the industry. I hope this information helps you for your search. 4100= better main bath, better garage space, slightly larger bedroom, lighter weight 4200= better living space, 2nd full bath, better kitchen, side patio, more storage, and 20,000GVWR