Clustering lets one server take over the duties of a second server when it fails.
Co-StandbyServer doesn't require the clustered servers to share the same configuration, to have one of the servers inactive until a failover, or to be placed closer together than the distance that Fast Ethernet requires. In most comparable solutions, the paired servers appear as separate systems to network users. But Co-StandbyServer uses aliases to treat them as a single entity. During testing, we logged on to the primary server and mapped three drives and a printer port. When we downed that server, Co-StandbyServer automatically switched us to the second server, retaining our mapped connections.