[ovirt-users] compatibility relationship between datacenter, ovirt and cluster

Hi, yesterday my ovirt was 3.3 my datacenter and cluster (compatibility version) was aligned with ovirt 3.3 today my ovirt is now 3.4. and my datacenter and cluster (compatibility version) remains 3.3 (with the option enabled to change for 3.4) browsing the ovirt admin page I see 2 occurrences of ovirt version: datacenter tab = 3.3 cluster tab =3.3 I would like to understand what means all these versions, the same version for a lot of important things, and how my ovirt works/behaves using different versions. all my doubts together : What means datacenter in version 3.3(or lower version) when ovirt is 3.4 ? what means cluster in version 3.3 when ovirt is 3.4? what means change the "compatibility version" for datacenter? what means change the "compatibility version" for cluster? thanks