how SEPM HA works is it active active or active pasive ?
The SEP client is supported in both Active/Active and Active/Passive clustering.
Yes both of OS version are same
Failover and load balancing installations are supported only when the original Symantec Endpoint Protection Manager uses Microsoft SQL Server.
https://www-secure.symantec.com/connect/forums/difference-between-replication-and-failover