Does it make a difference whether you die an Elder or High Priest? Do they perform different duties in the Spirit World?
It makes no difference to your salvation whether you die a worthy Elder or High Priest. For a little perspective, I refer you to Elder McConkie’s address Only an Elder:
“Brethren, what think ye of the office of an elder? Someone asks: ‘What office do you hold in the Church? What is your priesthood position?’ An answer comes: ‘Oh, I’m only an elder.’
Only an elder! Only the title by which a member of the Council of the Twelve is proud to be addressed; only the title which honors the President of the Church, who is designated by revelation as the first elder (see D&C 20:2, 5); only the office to which millions of persons are ordained in the vicarious ordinances of the holy temples.
Only an elder! Only the office which enables a man to enter the new and everlasting covenant of marriage and to have his wife and children bound to him with an everlasting tie; only the office which prepares a man to be a natural patriarch to his posterity and to hold dominion in the house of Israel forever; only the office required for the receipt of the fullness of the blessings in the house of the Lord; only the office which opens the door to eternal exaltation in the highest heaven of the celestial world, where man becomes as God is.
Only an elder! Only a person ordained to preach the gospel, build up the kingdom, and perfect the Saints; only a minister whose every word is scripture; only the holder of that office which carries the privilege of receiving the mysteries of the kingdom of heaven, of having the heavens opened, and of communing with the general assembly and Church of the Firstborn, and of enjoying the communion and presence of God the father and Jesus, the mediator of the new covenant. (See D&C 107:19.)
Only an elder! Every elder in the Church holds as much priesthood as the President of the Church. No apostle can or will rise higher in eternity than the faithful elder who lives the fullness of the gospel law.”
The responsibilities of Elders and High Priests in the next life have not been revealed to us.