The differences are plentiful: Durant plays for a team that just beat the Spurs (again), has a better core going forward, isn't from Texas and doesn't have family in the state.
I've also said with Aldridge, that it was more a marriage of convenience than anything, for both parties involved. It didn't set any precedent; it was a unique case where only the Spurs could offer everything he was said to be seeking.
Who doesn't profess to have "deep admiration for Popovich and the culture he's built"? Not that he or anyone doesn't, but it's also lip service. A lot of times, athletes just say what they're supposed to in a given situation.