In Lana's case, the change in hair style.
And here's a render with which I had a particularly hard time today. I wanted to show their facial expressions visible in the mirror, hence the problems. This is what the final result looks like, but it took me several hours and a lot of rendering attempts with different settings and different lighting angles.

Eh, this render is causing more problems. I am rendering the next one, and you will see the differences. This, I hope, will be the final version of this render.
Yeah, this is what it looks like when a dev wants to do something fast.