Clone vs Bkup

Hi
I'm feeling pretty stupid. I still can't figure out the diff. between backing up and cloning.
I have Acronis Corporate Pack and want to backup? my SBS 2003 and a workstation.
Seems to me I need to clone the machines each time I make a non data change. Like add an app. or hardware etc.
And, I should have a regular backup schedule for data etc.
True?
Is the clone the only way to have a second copy of EVERYTHING including the OS and all the applications, settings, registry etc.?
Thank you for your time