Always look to the KDP dashboard as the authoritative data source for conversions (sales and/or pages read). It would be highly unusual for the KDP and Ads dashboards to be identical. The Ads dashboard will only display a subset of your conversions, representing what it attributed to the ad during a 14-day time period. It does not include organic conversions that happened during that time. Thus, conversions on the KDP side should always be higher.
KDP or Ads Dashboard - Which should I believe?
Updated: Nov 9, 2021