Translators of the NASB seem to think that hieraeus should be translated priest ... and presbuteros should be translated elder ...
Ill go with them ...
"one who offers sacrifice and has the charge of things pertaining thereto," is used (a) of a "priest" of the pagan god Zeus, Acts 14:13; (b) of Jewish "priests," e.g., Matt. 8:4; 12:4,5; Luke 1:5, where allusion is made to the 24 courses of "priests" appointed for service in the Temple (cp. 1 Chron. 24:4ff.); John 1:19; Heb. 8:4; (c) of believers, Rev. 1:6; 5:10; 20:6. Israel was primarily designed as a nation to be a kingdom of "priests," offering service to God, e.g., Ex. 19:6; the Israelites having renounced their obligations, Ex. 20:19, the Aaronic priesthood was selected for the purpose, till Christ came to fulfil His ministry in offering up Himself; since then the Jewish priesthood has been abrogated, to be resumed nationally, on behalf of Gentiles, in the millenial kingdom, Is. 61:6; 66:21. Meanwhile all believers, from Jews and Gentiles, are constituted "a kingdom of priests," Rev. 1:6 (see above), "a holy priesthood," 1 Pet. 2:5, and "royal," 1 Pet. 2:9. The NT knows nothing of a sacerdotal class in contrast to the laity; all believers are commanded to offer the sacrifices mentioned in Rom. 12:1; Phil. 2:17; 4:18; Heb. 13:15,16; 1 Pet. 2:5; (d) of Christ, Heb. 5:6; 7:11,15,17,21; 8:4 (negatively); (e) of Melchizedek, as the forshadower of Christ, Heb. 7:1,3.
http://www2.mf.no/bibelprog/vines?word=%AFt0002209
an adjective, the comparative degree of presbus, "an old man, an elder," is used (a) of age, whether of the "elder" of two persons, Luke 15:25, or more, John 8:9, "the eldest;" or of a person advanced in life, a senior, Acts 2:17; in Heb. 11:2, the "elders" are the forefathers in Israel; so in Matt. 15:2; Mark 7:3,5; the feminine of the adjective is used of "elder" women in the churches, 1 Tim. 5:2, not in respect of position but in seniority of age; (b) of rank or positions of responsibility, (1) among Gentiles, as in the Sept. of Gen. 50:7; Num. 22:7; (2) in the Jewish nation, firstly, those who were the heads or leaders of the tribes and families, as of the seventy who assisted Moses, Num. 11:16; Deut. 27:1, and those assembled by Solomon; secondly, members of the Sanhedrin, consisting of the chief priests, "elders" and scribes, learned in Jewish law, e.g., Matt. 16:21; 26:47; thirdly, those who managed public affairs in the various cities, Luke 7:3; (3) in the Christian churches, those who, being raised up and qualified by the work of the Holy Spirit, were appointed to have the spiritual care of, and to exercise oversight over, the churches. To these the term "bishops," episkopoi, or "overseers," is applied (see Acts 20, ver. 17 with ver. 28, and Titus 1:5,7), the latter term indicating the nature of their work, presbuteroi their maturity of spirtual experience. The Divine arrangement seen throughout the NT was for a plurality of these to be appointed in each church, Acts 14:23; 20:17; Phil. 1:1; 1 Tim. 5:17; Titus 1:5. The duty of "elders" is described by the verb episkopeo. They were appointed according as they had given evidence of fulfilling the Divine qualifications, Titus 1:6-9; cp. 1 Tim. 3:1-7; 1 Pet. 5:2; (4) the twenty-four "elders" enthroned in heaven around the throne of God, Rev. 4:4,10; 5:5-14; 7:11,13; 11:16; 14:3; 19:4. The number twenty-four is representative of earthly conditions. The word "elder" is nowhere applied to angels. See OLD.
http://www2.mf.no/bibelprog/vines?word=%AFt0000866
At a minimum, it leaves one wondering why the normal Greek work for priest was not used of Christians, apart from the universal priesthood of the believer.
Also: http://www.biblestudytools.com/lexicons/greek/nas/presbuteros.html
http://www.biblestudytools.com/lexicons/greek/nas/hiereus.html