debsums compares the files installed by every .deb package against the checksums the package itself declares. Where AIDE asks whether anything changed since your snapshot, debsums asks a sharper question: does this binary still match what the distribution shipped? A modified file inside a system package is one of the clearer signals that something is wrong.
This page lists the packages with mismatches and the specific files inside them, so you can tell a rewritten binary from an edited configuration file at a glance.
Expect legitimate findings. Configuration files under /etc are meant to be edited and will show as changed the moment you configure anything, which is why they are usually filtered out. Some packages also generate files after installation that never match. The findings that deserve attention are executables in /usr/bin, /usr/sbin and /bin, and shared libraries — none of those have any business differing from the packaged version on a server you have not modified by hand.