Class A motor homes of similar size (length) to Class C generally have a higher GVWR. The fresh, grey, and black water along with the fuel capacities are generally much higher in a Class A. It's not a big deal unless you boon dock a lot versus RV Park camping. (full hookups) As previously mentioned, Class C MH's fall short of Class A's when you compare the dry storage and towing capacities.
In a Class A you usually sit much higher up so your view of the road/scenery is better but Class C's are generally safer for the front occupants if you are unfortunate enough to get in a front end collision.
Chum lee