In reality, yes, of course there is. The 10th best player in this draft will have a fairly significant edge on the 15th best player.
However, the player selected at #15 could of course be just as good, or better, than the 10th pick, because GMs get it wrong all the time.
For instance, in 1998, the best players in the draft were picked 9th and 10th. The Celtics having that 10th pick was golden; if they'd gotten the 15th pick, there was no franchise player left on the board. Before that draft, nobody was predicting that it was ten players deep, or that Pierce would fall that far.
Contrast that with the 2004 draft, where we picked Al Jefferson #15. If we had the #10 pick, it's highly likely that we end up with one of Robert Swift, Sebastian Telfair, or Luke Jackson. There, having the 15th pick was better, due to faulty talent evaluation.
So, the value of #15 vs. #10 this year depends upon the talent evaluation of those teams picking in front of us, and Danny's own talent evaluation. If Danny can grab the best player on the board, then #10 is going to end up being quite a bit more valuable than #15, and the same is probably true in any draft.