One usage divides game mechanics into three levels: ''Replacement rules'', ''abstractions'' and ''meta-techniques''.
'''[[Replacement rules]]''' are when a concept in the fiction is replaced with or simulated by something else. I.e. a boffer sword replaces a real sword. Sex is simulated by neck-massage. The player and the character experiences the same thing differently.
'''Abstractions''' are when the metatechnique itself is immanent in the fictional world. I.e. In this world latex is deadly and boffers kill or there is no sex, but Ars Amandi fulfills the same functions. In this, the experience of the character and the player are the same.