Eastern orthodox and Greek Church

Eastern orthodox noun - Derived from the Byzantine Church and adhering to Byzantine rites.

Greek Church and eastern orthodox are semantically related. In some cases you can replace phrase "Greek Church" with "Eastern orthodox", this phrases are similar.

Greek Church noun - State church of Greece; an autonomous part of the Eastern Orthodox Church.

Eastern orthodox and Greek Church are semantically related. You can use "Eastern orthodox" instead a noun phrase "Greek Church".