Sabarnadeb -
With regard to cloning the terms base/backing snapshot may be used interchangeably.
It's the snapshot from witch the inode for the clone has been copied.
A 'LUN clone' operation results in a 'Flexclone LUN'.
A LUN clone operation clones the LUN within the same volume.
A volume clone operation creates a new volume - a clone of the original volume.
This would include all LUNs, or in a NAS environment all files, that were in the source volume.
Wish I could show you the whiteboard I do in classes when I teach cloning !
I hope this response has been helpful to you.
At your service,
Eugene E. Kashpureff, Sr.
Independent NetApp Consultant http://www.linkedin.com/in/eugenekashpureff
Senior NetApp Instructor, IT Learning Solutions http://sg.itls.asia/netapp
(P.S. I appreciate 'kudos' on any helpful posts.)