Bishops and overseers and elders all refer to the same office, while nowhere does the NT teach a separate sacerdotal class of believers, corresponding to the Old Testament priesthood, kohen, for which the distinctive Greek word "hiereus" is uniquely used by the Holy Spirit in NT.
But who never uses that distinctive word for NT church pastors, and instead the words "episkopos" (superintendent or overseer, referring to function), and "presbuteros" (senior, in age, implying maturity, and or position) were used, with both referring to the same person in the pastoral office. (Titus 1:5,7; Acts 20:17,28)
All believers are called to sacrifice (Rm. 12:1; 15:16; Phil. 2:17; 4:18; Heb. 13:15,16; cf. 9:9) and all constitute the only priesthood (hieráteuma) in the NT church, that of all believers, (1Pt. 2:5,9; Re 1:6; 5:10; 20:6).
However, since in Catholicism presbyters are considered a distinctive sacerdotal class of believers then Catholicism translates the distinctive Greek word hiereus for their priests as a denoting this distinctive sacerdotal class, thereby losing the distinction the Holy Spirit provided by never distinctively using the term of hiereus for NT presbuteros, or describing as them as a distinctive sacerdotal class of believers.
You will never even see them described as conducting the Lord's supper in the only wholly inspired record of what the NT church believed (Acts - Revelation, including how they understood the gospels) of what the church did and how they understood the gospels. Though I am sure they did conduct this, yet they are not seen or charged with this in the epistles as being a unique and or primary function, nor preaching the Lord's supper as the means of regeneration, that of obtaining spiritual life.
Which is in contrast to presbuteros/episkopeos (same persons) being charged with and exampled as preaching the word as their primary active function, (2Tim. 4:2) feeding the flock thereby. (Acts 20:28) with believing the gospel being the means of regeneration, of obtaining spiritual life (Acts 10:43; 15:7-9; Eph. 1:13) and being nourished (1Tim. 4:6) and built up (Acts 20:32) for the word, is what is called spiritual food, "milk" (1Co. 3:22; 1Pt. 1:22) and "meat," (Heb. 5:12-14
Which is just one of the many
Catholic distinctives not manifest in that inspired record.