They are Roman collars. That being said, we must remember that the Roman collar is not just for priests. It is worn by deacons and brothers too. It is not blurring the lines in the sense that it is not just for priests.
The altar boy does not replace the cleric. The altar boys replaced the acolytes. Acolytes were not clerics. Many acolytes eventually became clerics, but not always. All monks and friars are acolytes, but only 1/3 are priests, none of permanent deacons and few are bishops.
The altar boy must wear whatever is determined by the priest who is celebrating the mass. The GIRM does not make a specific statement about what they must wear, only to say that the lines of the vestment must reflect dignity and beauty, without being ornate. This applies to the vestments of the deacon and the priest as well.
The rabbata (white collar) looks very high. I’m wondering if this is an adult size. These boys look very little.
Fraternally,
Br. JR, OSF