SolydX and SolydK are Debian-based distributions with the Xfce and KDE desktops respectively. SolydXK aims to be simple to use, providing an environment that is both stable and secure. SolydXK is an open-source alternative for small businesses, non-profit organisations and home users. The project started as an unofficial variant of Linux Mint's "Debian" edition with KDE as the default desktop, but it was later given its own identity as SolydK. SolydX was added after Linux Mint dropped its Debian-based flavour that used the Xfce desktop.
SolydK is a Debian based distribution with the KDE desktop. This is the big brother of the two and has all the bells and whistles.