I think the "A" has more interior room than a same size "C". "A" is built on a larger chassis than a "C" so potentially greater towing capacity.
Our first MH was a 21 ft Toyota Dolphin, micro class C, small but perfect for our trip to Alaska. And it got 15 mpg. One thing I liked about it, I could park it just about anywhere that you could park a full size car. I can't do that with our Mirada.
Alaska | Alaska Trip Log
Our 30 ft Mirada is similar to the toyhouse in the basic layout, i.e. kitchen, bench seat with table, and jackknife sofa.
But the Mirada has a full sized bedroom, a generator, shower, bath, and we can tow a car. And it gets about 8 mpg.