I recently used this line to look for differences:
diff -u <(grep '^[^#]' arrangements/EinsteinEvolve/GRHydro/test/balsara1_2d/grhydro\:\:bcons.y.asc | sort -u) <(grep '^[^#]' TEST/sim/GRHydro/balsara1_2d/grhydro\:\:bcons.y.asc | sort -u)
This removes all comments and empty lines, then sorts the output and removes duplicate lines (from different processes). The result is rather easy to interpret.
If one also deleted column 5 (?) containing the component number, then this would make the self-test independent of Carpet's process decomposition.