How so? The only significant differences I can think of are the location of the toilet, and the bed folding into the wall Murphy style.
Well, as one who has traveled many thousands of miles in both Amtrak and VIA roomettes, I also much prefer VIA's traditional roomette for three primary reasons:
1. The bed is MUCH better. It is wider and roomier at the head. It has a real mattress. I find it much easier to sleep on VIA's roomette berth and my sleep is more restful. It is also at exactly the same level as the window, so I can look out at night without propping myself up or craning my neck. The "Murphy" style bed with the release lever is much easier to handle myself, rather than the pull and push at the same time and watch your fingers abominable Amtrak mechanism.
2. The solid door makes me able to completely darken the room for night viewing. That is impossible now on Amtrak since they have gotten rid of the old "blackout" style curtains and replaced them with much thinner ones, especially on the Superliner I refurbs with the nuclear dawn aisle lighting.
3. Actual opaque, traditional railroad pull-down window blind. When I know there is going to be a late night stop with a lot of light, such as a late zero dark thirty arrival in Winnipeg, I pull it down and the room remains completely dark and my sleep is not disturbed. As opposed to, say, Sacramento, where the brilliant platform lights flooding in through the thin curtains always wakes me up.
I don't care about the in room "combolet" toilet. At night, I mostly go down to washroom at the other end of the car to answer nature's call anyway like I do on Amtrak, so that is pretty much a wash for me.