Service record/in game discrepancies

I don’t know if this has already been asked, but why are my kills and deaths different in the in-game service record then the online (halo waypoint) service record? Halotracker and online service record are the same for me but in-game the numbers are different. Does the in-game leave out certain playlists or what?

Sometimes the post game carnage and real game -Yoink!- add up.

> Sometimes the post game carnage and real game -Yoink!- add up.

I’ve noticed this alot but never bothered to count each kill in a replay to see which ones correct.

So which one is the more accurate?