144:8 If a kohein and a Yisrael are equal in their Torah knowledge, it’s a mitzvah to give precedence to the kohein, as per Leviticus 21:8, “he shall be holy to you.” The Sages explained this to mean that for holy matters, the kohein is the one designated. This includes being called first to the Torah, being the first speaker in a public gathering, speaking first in a meeting, having priority at a meal to recite Hamotzi and to lead bentching, etc. He should be given a nice portion before the other diners unless there is present a Yisrael who surpasses him in Torah knowledge. If this is the case, then the scholar should be given the nice portion first. However, when a kohein is partners with a Yisrael, there is no need to give him a nicer share. This is no honor to him because one who covets a superior portion will never see any benefit from it. If there is no kohein present, it’s appropriate to give precedence to a Levi over a Yisrael so long as they are equal in Torah knowledge.
144:9 It’s forbidden to use a kohein as a servant even nowadays; it is like misusing a sanctified object since “he shall be holy to you” and he is the one who offers the sacrifices. Even now, when there are no sacrifices, a kohein retains this holy status. However, if a kohein chooses to forgo his honor, he may do so and allow a Yisrael to use him as a servant. He may certainly give honor to a Yisrael and allow him precedence in the other ways we have mentioned.