The Top Tracks stats include the data of the following activities:
1) When someone downloaded a full release
2) When someone downloaded or streamed a track from a release
3) When someone streamed a track without a release
The third activity stems from platforms that do not link tracks to releases, such as: Content ID, Facebook, etc.
The Top Releases stats only include the data from the following activities:
1) When someone downloaded a full release
2) When someone downloaded or streamed a track from a release
This is why there is a slight discrepancy between the two.
Updated