Hello @saksham,
The component version you can check in the following way (for DIR, SD and FD):
bacula-dir -?
bacula-sd -?
bacula-fd -?
The upgrade process depends on the Bacula packages that you use. Usually with deb packages the process is automated and for rpm it requires manual updating Bacula SQL tables in the Bacula database.
For all cases, I encourage you to read the Bacula release notes. You can find it in the ReleaseNotes file attached to the Bacula sources. There is information about the upgrade and about the component compatibility.
Best regards,
Marcin Haba (gani)