No, Bradley's right, the boys definitely look younger. Especially Naruto, he looks like a little brat. If you look at Sakura's position, she can't be closer than the ninjas sitting on the grass, and they seem to be having a picnic right under the tree. To have a view broad enough to encompass the entire scene, the observer has to be quite far. At that distance, putting Sakura one or two metres closer does not account for that size difference at all.
I'm in no way familiar with Naruto, but I was assuming that those were kids in the tree, like some sort of "next generation" thing. I thought we were comparing Sakura to those two on the ground.