Arystarcus,
How do they differ from the ROAC and ROCOR?
After all these years, many feel, including myself, that the ROCOR is now heading away or are completly gone from Orthodoxy by communing with Cyprianites and talking about uniting with the MP and Monophysites. For many of these people, the ROAC is the true continuation of the ROCOR - thus you will see them called ROCOR(v); the "v" for their Archbishop Valentine.
What is the difference between the Matthewites, Lamians and the GOC?
This cuold be pages and pages long. In short, the Matthewites, ie Bishop Matthew, broke communion with the GOC of Greece in the 30's b/c they would not declare, at that time, the State Church of Greece was Graceless.
The "Lamains" are the result of 6 bishops leaving the GOC of Greece under Archbishop Chrysostomos II. Of these six, two repented and returned, two joined the heretic Bartholomew, and two "walled themselves off" in an anti-synod, becoming the "Lamians". The Lamains will forever have to stay "walled off" from the Church since they cannot make the charge of heresy.
What is the Chrysostomos Synod?
This is what the Lamians say they are "walled off" from - the GOC of Greece.
BTW, Orthos starts at 7:30 and Divine Liturgy about 9:30 AM on Sunday