Generally speaking, the ranks in the Church are difficult to distinguish, especially if the members of these ranks do not serve the Divine Liturgy or other services. However, the higher ranks in the Church can be distinguished by certain objects that they carry even outside the ministry.
The archpriest
The archpriest (protopresbyter) bears a cross on the chest. He is a distinguished priest, a title of honor given to non-monastic priests and is conferred by a bishop with the laying on of hands and prayer.
The archimandrite
The archimandrite also wears a cross on his chest, but the archimandrite is a monk and, at least on official occasions, wears epanokamelavkion (the veil of thin material covering the brimless hat called kalimavkion). The title of archimandrite was originally given to the leader of a brotherhood (αρχηγός της μάνδρας = αρχιμανδρίτης = arhigos tis mandras = archimandritis), that is to the Abbot, but today this title is conferred also as a title of honor in some local churches to someone who isn’t a leader of a brotherhood. Only the priests from the monks (hieromonks) can be archimandrites.
The bishops
The bishops wear an engolpion which is a round medallion. If they serve or are in official moments we can distinguish them better: The bishop when he serves has only one engolpion. The Metropolitan (the head of several bishops) has two and the head of a church (patriarch, archbishop) or the direct representative of the head of a church has three items: two engolpions and a cross.
Examples
In the photo we see from left to right, illustrating what I said above:
Metropolitan Chrysostom of Dodonis
Metropolitan Varnava of Naples, serving as the representative of the Ecumenical Patriarch
Archimandrite Ephraim, the abbot of the Vatopedi monastery, Mount Athos.
An archpriest from Greece
Behind Abbot Ephraim are two monks. They are recognized by the epanokamelavkion or koukoulion (the covering which we mentioned). From the garments we cannot say whether they are mere monks, hierodiacons or hieromonks (priest-monks).
The photo is took in the refectory of the Vatopedi monastery, Mount Athos.
— Source: asceticexperience.com