So conflict resolution's aim is to try and make every mods work as if it's the only mod installed, using all of its assets and tweaks freely. When mod authors create their mods, they test it to work in their environment, but your environment is not necessarily the same as their environment, why ? Because in their environments, their mod works freely as nothing conflicts with its working, but in your environment, you might have many mods conflicting with the mod. Said variable could be a mesh or a texture as well as a plugin or INI file. Likewise, two mods that affect the same game variable are strictly defined as incompatible, which is more often termed a conflict.
Strictly defined, two mods are compatible if they do not attempt to alter the same game variable.