You have two choices that I can see if you don't want to re-burn and re-verify.
Mount the ISO and the DVD and do a recursive diff of the two file systems. For example, if the DVD is
/Volumes/DVD and the ISO is
diff --recursive /Volumes/DVD /Volumes/ISO
Compare the MD5 sums of all the data on the two images. So:
dd if=/dev/disk1 bs=2048 count=169383 | md5
I'd take option #2 over #1 personally, though both are less than great ways to do a comparison.
You could also try exploiting
rsync to do the comparison instead of using
diff. If you ran
rsync with the
--dry-run options what you'd get back is a list of transfers that rsync thinks it needs to make to make the two file trees look the same.