Sora and Riku in 3D

I know this might seem a bit dumb of me to ask, since I'm sure this was discussed by the time this game first came out, but how come Sora and Riku seem to have different 2 different models in KH3D? Maybe models is the wrong word, but I don't have the right terminology for these kinds of things, and it's the only word that comes to mind. Here's a picture of what I mean.



In it we see a picture of Sora and Riku before and after they go to sleep. What I'm talking about is why they seem so completely different. That's why I ask if they're using 2 models for both of them. The hair is different, the eyes are different, heck, I think even the facial features are slightly different, and now that I look at it, their necks got skinnier too.....didn't notice that one before.

But did they actually use 2 different models? Because I'm quite curious on this now and want to know the answer to it.

 

The bottom models are them in their current forms as age 15 and 16
KH3D had them return to 14 and 15 respectively, so they used their 'child' models

 

Remember that the in-game characters are the younger versions, and that the exam (somehow) takes place in the past immediately after the island was destroyed. Whereas the older versions that we see with Yen-Sid are the current versions. Basically the older versions are a framing device for the game.

 

You are correct, those are two completely different character models, not just a texture swap or the like. And the why is what is said above plus the change in outfit.