RC, there is only one Sacrament of Holy Orders. JP2 and B16 and conservative Catholics contend that women may not receive that sacrament because Jesus set us a binding example when he appointed only men as apostles. 

That argument fails if it can be PROVEN that at some time in our past women did in fact receive that sacrament, whether as deacon or priest or bishop. The evidence for early women priests is suggestive but not conclusive. The evidence for woman deacons until at least until the 8th century and perhaps as late as the 12th is, IMHO, conclusive. For a sketch of the evidence, the truth you crave, see my comment here that begins "Part 1"