Check this link, it answers your question:
https://www.ancient-buddhist-texts.net/Reference/Sutta-PTS.htm
In short, the sutta numbering SuttaCentral uses is the correct one. The other numbering you find refers to Pali Text Society numbering, which was closely related to the volume page number in which you find the sutta in question.
To know more, check this as well:
https://suttacentral.net/sutta_numbering