Windows 7: Difference between system image, system rest and backup

Can some one tell me what the differences are between system image, system restore and system backup.

Also I made a system image and stored the file on an external drive and can't find the image file. Can someone tell me how I can find the file - did a search and organized the drive by date and could not find the file.

System Image is a copy of your hard drive
System restore copies your OS
Back up and restore copies your personal doucments etc

On my system the file is windows image and backup.

I have my hard drive partitioned. System image then will copy each partition or the partitions I select. Is this correct? Where is the image file located and what is its extension? I can't seem to find it when I perform a system image. System restore only copies the partition with the operating system. Is this correct?

Backup only copies the data files. Is this correct? Whenever Iperform a backup it never completes? Can you explain why this happens? The drive I am saving the backup has plenty of space.

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Go into Folder Options and un-hide extensions for known file types. Also make hidden files and folders visible and see if that helps.

Did not help

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I confirmed that Windows 7 uses the standard ISO extension for the image. I suggest trying it again. First check how much free space is available on the external drive. Then create the image and check the free space again. That should make it clear whether or not the image was created since it will be some number of gigabytes. Then try doing a wildcard search for the file - "*.iso" (leave off the quotes)

Hope this helps.

I hope I am not being pedantic and neither is this a criticism (often it's the terminology used) but is this actually the case? Does SR not return your machine to a previously good know working state. Or is this the same thing? Thanks.

It brings you back to a good known working state (restore point).

Agreed and thanks; so was the system restore about OS you were referring to something else rich (in your initial answer to the OP? )