A lay minister is not always an extraordinary minister.
For example, who is the ordinary minister to proclaim the first reading?
The priest? No.
The deacon? No, he proclaims the Gospel.
The bishop? No.
The correct person to do this is a lay minister, called an instituted lector.
From the 2002 General Instruction of the Roman Missal (GIRM) approved for the USA, which can be accessed from romanrite.com/girm.html :
“99. The lector is instituted to proclaim the readings from Sacred Scripture, with the exception of the Gospel. He may also announce the intentions for the Prayer of the Faithful and, in the absence of a psalmist, proclaim the Psalm between the readings.”
The term “commissioned” is used in the GIRM for a minister who is not instituted:
“101. In the absence of an instituted lector, other laypersons may be commissioned to proclaim the readings from Sacred Scripture. They should be truly suited to perform this function and should receive careful preparation, so that the faithful by listening to the readings from the sacred texts may develop in their hearts a warm and living love for Sacred Scripture.”
The instituted lector has a proper ceremony to be instituted. The “commissioned lector” is appointed, but not with this proper ceremony that is used worldwide.
But in the USA’s Book of Blessing there is a ceremony for blessing readers who are not instituted. The ceremony is not in the Latin edition of the Book of Blesssings, but to my knowledge, only the USA’s. It has in the introduction:
“1828 This order is not intended for the institution of readers by the bishop, who uses the rite contained in the Roman Pontifical. Rather, this blessing is for parish readers who have the responsibility of proclaiming the Scriptures at Mass and other liturgical services. …”.
(Book of Blessings, Liturgical Press, Minnesota, 1989, ISBN 0-8146-1875-8, page 691.)