Lies am besten hierzu die Debian-Richtlinien, Kapitel 10.7, hier ein
Auszug:
10.7.1 Definitions
configuration file
A file that affects the operation of a program, or provides
site- or host-specific information, or otherwise customizes the
behavior of a program. Typically, configuration files are
intended to be modified by the system administrator (if needed
or desired) to conform to local policy or to provide more
useful site-specific behavior.
conffile
A file listed in a package's conffiles file, and is treated
specially by dpkg (see Details of configuration, Section 6.7).
The distinction between these two is important; they are not
interchangeable concepts. Almost all conffiles are configuration
files, but many configuration files are not conffiles.
Insbesondere der letzte Absatz ist in diesem Zusammenhang wichtig!