These are two different operating systems - Czechoslovak and Russian.
MOS also stands for "Machine Operating System (MOS)" for Acorn computers.
Czechoslovak system from VÚMS for computer EC 1021 (ZPA 6000/20) from VÚMS. The minimum RAM size requirement was 16 KiB.
Russian OS based on V7 Unix, "developed" at NICEVT, USSR, based on UTS.
Runs on EC 1045
Among the successors of MOS are MNOS, DEMOS, INMOS.