Ultimately, the phrasing (of work done) depends on who is really driving the work and what they really want to be done.
For instance, many on this site would argue that the work at Augusta would be a renovation, not a restoration, because of the club's (and Fazio's) apparent desire to alter the course for the sake of toughening next years tournament and not for original design intent.
In the case of a course such as Yale, the recent work seems to be driven by the desire to "restore" the architectural integrity of Raynor/MacDonald.
Examples aside, to elaborate on the opening thought:
A green committee may have the itch to "do something" to their course that would not accentuate the original design intent but would accomodate modern play (ie cartpaths, bunker removal, green regrading, etc.) If they are dead-set on doing the work no architect can convince them otherwise. This work would be what, renovation?
A superintendent wants to regrade the surrounds of a green to eliminate the build-up of decades of topdressing. Because of 80 years of topdressing, the slopes have become scalped and burnt out. The super enlists a contractor to soften the slopes so that he can mow the surrounds at fairway height (its a Ross course). This work would be what, restoration?
Edit:
Does the historic era or relevance of the course matter in determining the phrasing of work being done?
Atlantic City is an old course, what was that work?
Or, does the driving force (persons) behind the work determine it? Can an old course be "renovated" because there isn't the desire to "restore"?