Hi and welcome.
Ubuntu comes with Gnome as GUI, Kubuntu comes with KDE as GUI. Thats it!
I would say go for KDE, which offers alot of user friendly interfaces for different settings on your PC. You can choose to let it behave like windows.
Only thing about KDE is that it eats alot of ressources, it's pretty demanding i think, but if your PC is fairly new this shouldn't be a problem.