This is a bit confusing terminology.
Here it is discussed on a AN6.120 which says that these lay people realized nibbāna, but they are not yet arahants.
As far as I can see, the chinese agrees with the Pāḷi.
Stream winners see Nibbāna, their becoming/existence is not yet ceased. Seeing nibbāna is realizing nibbāna. Attained to the deathless.
Only arahant can immerse in nibbāna with the body. (enjoy freedom from greed, hatred, delusion).
Existence ceases at parinibbāna.
