I noticed that there is a new distro called KDE Neon, but to me, it sounds just like Kubuntu, I don't know what the differences between it and Kubuntu are and whether one has any advantages/disadvantages over the other.
KDE neon's foundations will be the Ubuntu LTS version, they will not change unless necessary or a new version comes along. The KDE software on top of the foundations however keeps getting updated by default whenever new stable releases are done. The primary focus of development is getting the latest stable KDE software to the users of KDE neon.
Kubuntu on the other hand moves along with the Ubuntu releases in between LTS releases and each Kubuntu release has set versions of KDE software it releases with. Once released no new feature versions are added. The primary focus of development is preparing the upcoming (every 6 months) Kubuntu version.