Not bad, however you gotta work more on shadows cause I don't know if that's soft or cell shade. Moreover I can hardly find where is the lightsource cause the same shadows are a bit thrown off everywhere, don't forget that it's the most important, decide a lightsource and then don't change it no matter what happens.
As for the night version you just changed the background and lessened the general light right? That's not bad, you could also add some moonlight reflects, that would make it look even better.