Data replication:

In data replication, the destination share is available all the time - however, it should be used only for backup purposes because if you change some files, they will be replaced during the next synchronization.

Volume replication:

In volume replication, the volume will remain unavailable until the destination volume has been switched to source mode. The replication itself is continuous - it can be stopped but it does not end on its own.

You can also access the data from the destination volume by assigning a snapshot to it.

Please note that if volume replication is stopped and the current state of the data is inconsistent, your data may be corrupted.