Hard to say for sure, but I think you could call the garment a 'cassock' and 'mitre'. The cylindrical headgear of Eastern Orthodox ministers is called a 'kamilavka', I have just discovered, but I can't find an English translation - there may not be one. It seems that this is the word used in English, too. Lovely drawing, by the way. A budding artist.

Non-liturgical vestments

Note: Ignore 'and mitre' in my post. It was part of a previous answer which should have been deleted.

What is the man in black wearing? Avatar