Refer to my run expectancy article from Sabermetrics 101 for more information.
Run expectancy refers to the average number of runs scored in a given situation (generally for the rest of the inning, but if including inning number, perhaps it would be for the rest of the game) based on context-aware factors such as base-out state, inning, etc. Generally, factors which take into account the quality of teams are not included. I would personally label any stat which does that as being a method of projection rather than a run expectancy stat.