The quality of the shows are totally different... As I said before, Dave IS an entertainer, reminds me a little bit of Robbie Williams in that sense.
But Sumner can't entertain even the pensioners his age that go to his concerts. It also doesn't help when you insult your audience or go on stage totally drunk/high like the 81 Glastonbury festival. If you watch the footage on YT there was a lot of people saying they'd ask for their money back if there.