Editing RPG System Symmetries (section)

===Resolution System===
That is, using the same mechanics to describe different kinds of activities and conflicts. It's not as easy as rolling d20 (or 3d6, or pool of d10s, or whatever) for everything - it's also about similar granularity, similar relation to character's stats, etc. If a game uses a map, describes attacks and counts HPs in combat while it resolves social conflicts with a single roll (or a few rolls, counting successes), it does not have a resolution system symmetry.

No game I know of fully exhibits this symmetry, though most games try.