In the churches of Greek Orthodoxy, every diocese is a metropolis, headed by a metropolitan while auxiliary bishops are the only non-metropolitan bishops.
In non-Greek Orthodox churches, mainly Slavic Orthodox, the title of Metropolitan is given to the heads of autocephalous churches or of a few important episcopal sees.[1]
There are very few suffragan sees that have the rank of archdiocese, such as the Archdiocese of Avignon that is a suffragan of the Archdiocese of Marseille.[2] Other non-metropolitan archdioceses are directly subject to the Holy See and are merely "aggregated" to an ecclesiastical province, without being part of it.