Pretty straightforward. These two are easily the most infamous rock operas ever created, each exploring a character trapped in his own mind, with absent father figures (to an extent) and they each become some kind of superstar with slightly varying results. For my money, The Wall is more cinematic and a bit easier to follow, and slightly more captivating, but Tommy's greatness cannot be discounted. With better production especially, who knows how much greater it's impact might've even been.