What are the responsibilities of a conference's program chair versus its general chair? Computer science conferences like STOC and FOCS list separate program and general chairs.
A guess would be that the program chair is in charge of the technical content (which papers are accepted, etc.) whereas the general chair is in charge of administrative aspects. However, some conferences, like FOCS, list a third group of local arrangements chairs who sound like they are in charge of the administrative side of the conference. Others only have one group of undifferentiated "chairs".
What do each of these jobs entail? Are they considered "equal" in terms of service to the community?