Comment 1 for bug 112619

I can confirm that this is inconsistent. However, debuild calls dpkg-buildpackage, so the environment variables are valid anyway. Either using debuild everywhere or dpkg-buildpackage everywhere should both be fine.

Roughly, debuild calls dpkg-buildpackage, runs lintian/linda, and signs the .changes/.dsc files using debsign (instead of letting dpkg-buildpackage do the signing itself). Some package guides use only debuild, other guides use only dpkg-buildpackage, personally I don't know which way is considered the canonical way.