In our common understanding the sotāpanna or stream-enterer is the first category of nobles ones or aryas. (See for two occasionally mentioned two stages before sotāpatti here: https://discourse.suttacentral.net/t/faith-follower-dhamma-follower). Usually we say that a sotāpanna has at most seven more lives to live, yes in a few suttas we have a further discrimination of the sotāpanna into three distinct levels – unfortunately without much explanation. Hence I won’t go into the small differences between the suttas.
The material we find in the following suttas is very similar in a longer list of stages along with different nibbāna attainments. The sources are SN 48.24, AN 3.87, AN 3.88, AN 9.12, AN 10.63, AN 10.64. Mostly they are just mentioned by name, only AN 3.87/88 and AN 9.12 add a short description.
The three levels are in ascending order:
The seven-times-at-most attainer (sattakkhattuparamo): “who, after roaming and wandering on among devas and humans seven times at most, makes an end of suffering” (additionally mentioned in SN 56.49 - SN 56.60 in the same repetitive way)
The family-to-family attainer (kolaṃkolo, kula = family, house): “who, after roaming and wandering on among good families two or three times, makes an end of suffering”
The one-seed attainer (ekabījī): “who, after being reborn once more in human existence, makes an end of suffering”
Maybe these few appearances in the AN and SN were too vague for the editors to include them into the MN or DN. At least they got picked up again in the KN a few times…
[Edit: Does anyone know if our idea of a sotapanna getting reborn max. seven times - and thus singling out one type - is basically commentarial? I know it’s mentioned a few times more in the suttas, but the certainty with which the concept is communicated, is it EBT or later?]