They're only vaugely
the same clothes. But, yes, they are very different. As I've said many times before I think the ending being a dream sort of cheats us out of Cobb's character arc and what he wants. He's been comitted to getting back to his children and seeing them in his dreams wasn't good enough for him. But the children are very clearly in different clothes and appear to even be a bit older. He's clearly not been gone long.
The ending being a dream sort-of makes his whole arc -and the whole movie- pointless. The whole mission was to get back to his kids, it's why he took it and it's why he didn't want them to turn around in his dreams. Dreaming them simply wasn't good enough. It's a kick to his balls to make them still a dream at the end of the movie when he thinks he has won.
He also makes the point of telling Ellen Page that you never see a dream from it's begining, you simply drop into the middle of it. This is shown nicely in the movie he recalls being on the plane, his landing, going through security, driving home, and then entering his home. He's not simply dropped into being home with the kids.
For my money, the ending is real for it not to be is to defeat all of his character motivation and his "prize" for getting it done is to not have what he wanted? Depressing.
I will, however, argue that at the end of the movie he's "as back in reality as much as we thought he was in the whole time anyway."