The diff command tells you what files were changed/added/deleted between snapshots.
#list snapshots of a dataset
zfs list -rt snapshot | grep zpool/dataset
#choose two snapshots and use the diff command
zfs diff -FH zpool/dataset@zfs-auto-snap_monthly-2020-03-01-0552 zpool/dataset@zfs-auto-snap_monthly-2020-04-01-0452
The diff command can also show the difference between a snapshot and a current dataset.
zfs diff -FH zpool/dataset@zfs-auto-snap_monthly-2020-03-01-0552 zpool/dataset
The first column indicates the type of change:
- The path has been removed
+ The path has been created
M The path has been modified
R The path has been renamed
The second column indicates the file type, similar to ls. For further information have a look into the zfs man page.