Halakhah for Yoma 47:2

And [the garments] of the high priest are eight, and their names are like this: robe (ketonet), trousers (mikhnasayim) and sash (avnet) - like the names of the three of the regular priest - and mitsnefet (miter) was for the high priest instead of the turban of the regular priest. As this and that were [both] placed on the head, except that the the miter is made like a long type of cloth that women coil around their heads - and the high priest would coil himself with it - but the turban is made like a type of hat (that does not require coiling). Behold, [these] four of the high priest, which were only of linen, were white, six-stranded and embroidered, but their embroidery was not similar to the embroidery of the regular priest's sash. And he also had four others of gold and their names were breastplate (choshen), apron (ephod), coat (me'il) [and] headband (tsits). And he would do the external service with all of the eight, but inside - which is past the partition - he would never serve with anything but the [linen] clothes. And after he served with them for one Yom Kippur, he does not repeat to ever serve with them (Yoma 24a), as it is stated (Leviticus 16:3), "and he leaves them there." And anytime a priest - whether a regular or a high [priest] - serves with less than the clothes that are designated for that service, or more than them, his service is disqualified. And he is also liable for the death penalty by the hand of the Heavens, as our rabbis, may their memory be blessed, learned (Sanhedrin 83b, Zevachim 17b-18a) from "And you shall gird them with a sash [...] and they would have priesthood" (Exodus 29:9) - at the time when their clothes are upon them, their priesthood is upon them; when their clothes are not upon them, their priesthood is not upon them. And they are [hence] considered like a stranger (a non-priest) who transgresses, which is [punishable] by death. [These] and the rest of its details are elucidated in the second chapter of Zevachim and in places in Yoma and Sukkah (see Mishneh Torah, Laws of Vessels of the Sanctuary and Those who Serve Therein 10).