APK updates showing on Aurora (3rd-party store) before Play Store

I noticed this yesterday. I went onto Play Store and had "10 app updates available". I then went on to Aurora Store and there were "125 app updates available". I checked the version number of a few apps online, and it did seem as though the updates were legitimate. My questions: * Are the updates on Aurora Store legitimate? * And, if so, why are they not showing on Play Store?