Function and Risk
These things always get complicated when you make a definition based on multiple levels of requirement.
A backup is something you can recover from - copy or otherwise including snap as long as the data is in a proper consistant state and ties to a Point in Time.
An efftective backup is one that you can recover from quickly
an efficient backup is one that consumes little resource - effort to create or restore, and the media to contain it is cost effective - so space efficient on disk or low cost per GB on Tape.
A backup is prone to risk, so to reduce risk you go down the path of copying to other media, removing from site, hiding under bed etc.
Many modern solutions are very efficint in replicating PIT copies to offsite media.
Best case is you want both - fast recovery without copying etc - so work out how to achieve the best mix you can afford.
Just because I did not buy backup software does not mean I cannot produce a backup, as backups existed before backup software.
Biting the hand that feeds IT
