Great, thanks for the reply.
Apparently this is a case of ESRI calling it one thing, then changing the name of it later. This makes it hard for newbies like me to follow.
You might also come across the following link to the GeoServices REST Specification: GeoServices This was an attempt from Esri to standardize the geoservices services. The specifications unfortunately never found their way into the set of OGC specs.