EMC RP4Vm is a complete replication software suite. You can create consistency groups based, run failover tests, and perform actual failovers. The replication is occurs at the hypervisor level with its RP splitter component.
SRM is more like an orchestration software suite, where you can create groups of VMs to fail over and perform certain tasks based on your needs. But you will need to use either vSphere Replication or the replication software on your SAN.