Orthodox: (from Greek ὀρθός, orthos (“right”, “true”, “straight”) and δόξα, doxa (“opinion” or “belief”, related to dokein, “to think”) in one sense can be understood as adherence to accepted norms, more specifically to creeds, especially with respect to belief in God.  The word was first used in early 4th-century to describe those who confessed the faith upheld by the Fathers of the First Council of Nicaea (325). 

Ethos: (ἦθος, ἔθος, plurals: ethe (ἤθη), ethea (ἤθεα)) is a Greek word originally meaning “accustomed place” (as in ἤθεα ἵππων “the habitat of horses”, Iliad 6.511), “custom, habit”, equivalent to Latin mores. Ethos forms the root of ethikos (ἠθικός), meaning “moral, showing moral character”.