Same dates and filters: compare reports for the same date range, store and filters.

Trading day: reports start at your Start Trading Time (Configuration > Company Profile), not midnight. Late-night sales may fall in the next day.

Unsynced orders: if a device was offline, its orders appear once they sync. See How do I sync Unsynced Orders?

Refunds and voids: some reports show gross sales, others net of refunds. Check which you are comparing.

Split payments: one order paid two ways appears under both payment types.

Cash: cash figures depend on the register being opened and closed each day with the counted amount. Check the close-register report and its variance reason.

Settlement vs sales: card settlements arrive later and exclude cash. See Why your sales don't match your settlement.