Here's how to remove the timing information to have a clean, diff-compatible dmesg log:
sed 's/^...............//'The command basically removes the first (number of dots ".") characters of every line.
Then you can use diff to compare the dmesg files side by side:
diff -y -w -B --suppress-common-lines dmesg-A dmesg-BOf course this is still not magic, but at least now diff can filter out a lot of similarities for you.