@Rishi,
As said by Nicolai there is no point in digging the older version capabilities as already know that older version are out-of-support. You should concentrate on the current version.
Then also for your interest, below mentioned is the link where you'll get all NBU docs. It is really a huge list out there :)
So you can go ahead and read the TN of whatever the version you want and compare them.
Published Documents and Files for NetBackup Enterprise Server
Happy Reading ;)
Do close this thread if your question is answered.