The virt-diff command-line tool can be used to list the differences between files in two virtual machines or disk images. The output shows the changes to a virtual machine's disk images after it has been running. The command can also be used to show the difference between overlays1. To specify two guests, you have to use the -a or -d option for the first guest, and the -A or -D option for the second guest. For example: virt-diff -a old.img -A new.img1. Therefore, the correct command to list all differences between the disk images vm1-snap.img and vm1.img is: virt-diff -a vm1-snap.img -A vm1.img. The other commands are not related to finding differences between disk images. virt-delta is a tool to create delta disks from two disk images2. virt-cp-in is a tool to copy files and directories into a virtual machine disk image3. virt-cmp is a tool to compare two files or directories in a virtual machine disk image4. virt-history is a tool to show the history of a virtual machine disk image5. References: * 21.13. virt-diff: Listing the Differences between Virtual Machine Files ... * 21.14. virt-delta: Creating Delta Disks from Two Disk Images ... * 21.6. virt-cp-in: Copying Files and Directories into a Virtual Machine Disk Image ... * 21.7. virt-cmp: Comparing Two Files or Directories in a Virtual Machine Disk Image ... * 21.8. virt-history: Showing the History of a Virtual Machine Disk Image ...
