We offer two types of virtual servers backends. LXD and KVM.
KVM is an the industry standard with good track record for reliability and performance. CPU, memory are typically dedicated to the VPS but not in every case.
LXD is a newer technology which better leverages a server's capabilities, providing near bare metal performance with lower OS overhead. So your linux VPS should run as fast as it would if it was on similar spec'd physical server.
On the front end, the user sees the exact same default Linux install. Ubuntu, CentOS, Debian all work equally well on either version.