Check the furniture - I think they started using the new residential grade furniture in '14 from what I recently looked at. Big big difference. You loose the under furniture storage, but better durability and comfort is more that worth it.
Check the slide out motors - changed the size (larger) in either '13 or '14. I know they are larger in the '14.
Changed the solid surface counter tops in '14, I actually liked the rounded edge style they used in '13 better
Added 12v radio in either '13 or '14, I know it is in the '14. Was told previous it was only 110v
No ice makers in '14 up to this point - issues with water lines and the slide.
Just purchased a 2014 Voltage 3895 after several weeks of painstaking comparing and shopping.
If I remember any changes or differences I post.