The difference is that the Stones show are filled with a bunch of yuppie assholes who don't have a problem shelling out $200 to see a collection of washed-up senior citizens tread through the same old crap, and take bathroom breaks during the, what, 4 new songs that the band plays on a nightly basis? These are the same douchebags that pay to see The Eagles.
The Stones may be the elder statesmen, but U2 is still the biggest band in the world, simply because their new material is outselling the Stones 5 times over. Also, the Grammy attention U2 just received is colossal compared to the measly 1 nomination that the Stones had. The record-buying public thinks U2 is bigger, the industry thinks they are bigger. A bunch of middle-aged white people going to stadium shows does not put the Stones at the top of any popularity list, beachfront show in Brazil or no.
And I'm not a fan of The Dave Matthews Band, but aren't they pretty big worldwide at this point? And while I hate Oasis with a passion, I would say they are still more popular than R.E.M. on a ticket and album sales basis.