The Roman Missal’s Order of Mass has for one form of Penitential Act:
"6. The priest invites the faithful to make the Penitential Act:
Brethren (brothers and sisters), let us acknowledge our sins and so prepare ourselves to celebrate the sacred mysteries.
A brief pause for silence follows.
The Priest, or a Deacon or another minister, then says the following or other invocations with Kyrie, eleison (Lord have mercy):
You were sent to heal the contrite of heart: …".
The altar server is “another minister”.
The Book of Blessings, approved for the USA on 27 January 1989, has a blessing for altar servers, sacristans, musicians and ushers. Its introduction includes:
“1848 Among the liturgical ministries exercised by lay persons are those of altar server (acolyte), sacristan, musician …”. (Book of Blessings, published by Liturgical Press, 1989, ISBN 0814618758, page 699.)
From the context it is clear that term “acolyte” is being used for those who are not Instituted Acolytes. So the terms “acolyte” and “altar server” are being used interchangeably in a document approved by the Vatican for the Roman Rite, in the USA.