Those particular designations are vendor shorthand designations and not part of the Muramatsu mdoel names To be sure, you should ask the vendor. However, for most places:
C= C foot
B = B foot
E = Split-E mechanism
O = Offset G
So, most likely, for the examples you gave, the RCE has inline G and the RCEO has offset G.
"Never give a flute player a screwdriver."
--anonymous--