Discrepancy of metrics between reports
I exported report from GA for date range of one day only ( 01/07/2017) and for two days (01/07/2017-02/07/2017). Both of the reports contains the same settings, segments, dimensions and metrics. The numbers of the metrics (such as sessions, bounces, users, time on page, etc.) at the first report were different than the numbers at the second report, which I filter for the date of the first report (01/07/2017). For example, at the first report the sum of the sessions was 3992, and at the second report it was 3976, for the same date.
Both of the reports don't exceed the 1000 rows. Can you tell me what is the reason for this? If you need any further information I'll be happy to give you.