Is confirmation part of the Presbyterian Church in America (PCA) doctrine? In my research I have concluded that infant-baptisms and confirmations are practiced in the PCA, however it's not clear whether the latter is a necessary part of PCA doctrine.

The clarify, I regard confirmation as the one-off reaffirmation of the public profession that was made on behalf of the individual's parents and godparents during infant-baptism.

In the comments of this answer there is a dispute over confirmation versus a "public profession of faith". If this distinction does exist, what is the difference?

If confirmation or a similar practice is consistent throughout the PCA, what are the characteristics of it? What sets it apart from other denominations?
Chapter 57 from The Book of Church Order--part of the PCA's doctrinal standards, along with the Westminster Confession of Faith--(a link to such in pdf format can be found here) is titled "The Admission of Persons to Sealing Ordinances".

Children who have been infant-baptised are not to take part in communion:


  57-1.  Believers’ children within the Visible Church, and especially
  those  dedicated to God in Baptism, are non-communing members under
  the care of  the Church. They are to be taught to love God, and to
  obey and serve the  Lord Jesus Christ. When they are able to understand
  the Gospel, they should  be earnestly reminded that they are members
  of the Church by birthright, and  that it is their duty and privilege
  personally to accept Christ, to confess Him  before men, and to seek
  admission to the Lord’s Supper.


Each congregation (represented by a council of elected elders) decides when such a person is ready to received communion:


  57-2.  The time when young persons come to understand the Gospel
  cannot  be precisely fixed. This must be left to the prudence of the
  Session, whose  office it is to judge, after careful examination, the
  qualifications of those who  apply for admission to sealing
  ordinances.


At this time a public profession is recommended but not necessary:


  57-4.  It is recommended, as edifying and proper, that baptized
  persons,  when admitted by the Session to the Lord’s Supper, make a
  public profession  of their faith in the presence of the
  congregation. But in all cases, there should be a clear recognition
  of their previous relation to the church as  baptized members.


So the PCA does have a process of confirmation however it is not necessary public and it is at the discretion of the congregation (via the elders) as to the nature of confirmation - whether classes are required, who will be admitted, whether there will be a ceremony. In practice many churches do require and offer classes for confirmees.