How will we reconcile this Pasuk, which implies that the belt of the Kohen Gadol and that of the Kohanim Hedyotos were identical, with the Pasuk in Terumah 28:40, which implies that all the Begadim of the Kohen Hedyot were made exclusively of linen?
Ramban: This seeming discrepancy is the source of the Machlokes Tana'im in Yoma, 12a, as to whether the two belts were identical or not. 1
QUESTIONS ON RASHI
Rashi writes in Yoma 6a that one opinion holds that a Kohen Hedyot's belt was made of pure linen. How will he explain the Gemara in Erchin 3b, which states that Kil'ayim is permitted to [all] Kohanim? Moreover, the previts Pasuk mentioned the Migba'as (of a Kohen Hedyot), and here it says that there was wool in the belt?
Moshav Zekenim: Kil'ayim is permitted to some Kohanim - a Kohen Gadol, and the current Pasuk is discussing only a Kohen Gadol.
Moshav Zekenim (citing R Aharon): Everyone agrees that a Kohen Hedyot's belt contained wool, and they are arguing over whether or not a Kohen Hedyot may serve with the linen belt that the Kohen Gadol wore on Yom Kipur. 1
Moshav Zekenim: According to that, we must switch the text of other Gemaros - It is difficult to say that.