The difference doesn't matter that much because the AI is usually adjusted down across the board so you're left with everything in the same position...
It does matter! its an 8mil difference..
and its not adjusted its rounded like DS is 23.7 rounded to 24...
I mean the adjustment between BDS and Mediabase numbers... You generally just multiply the Mediabase AI by .75 so the difference is proportional. It would be important if DS had lower AI on Billboard while everything else was the same compared to Mediabase, but that's not the case.
It's not like Dark Side is the only song with a lower AI though.
Obviously, all the numbers are much less on Nielsen. I don't get the point of this.
Exactly all of the numbers are much less, but BILLBOARD uses Nielsen and therefore Nielsen is the one that accounts and not mediabase...
DS AI is 23.7 on Nielsen and billboard rounds it to 24.0 so therefore DS AI is 24 and not 32...
I don't think anyone really knows if one is really more or less accurate than the other, they just monitor different stations. Mediabase monitors more overall though so the AI they calculate is higher.
Almost 20 spots! 
sleeper hit on its way!