The "Display sums on results pages" option reflects the sum of all elements displayed from your paginated, filtered dataset.
If you use filters and/or specify a limited number of rows in your dataset, the "'Total' rows" will take these actions into account. For example, in the case of a Country/Visits dataset, if you use a filter on the Country dimension in order to limit results to France and Germany, the "'Total' rows" will be the sum of visits coming only from France and Germany.
Tip: You can't combine the evolution mode with the "'Total' rows" option.
The "Sum of all elements" option reflects the sum of all elements in your dataset, not taking into account any filters or pagination.
Tip: If your dataset contains more than 45,000 rows, the sum of your data will reflect your entire dataset (45,000 rows), not only the first 10,000 rows.
The option "Site reference" reflects the total of metrics of the reference site. This option enables you to identify the proportion of data contained in your call with regards to the total of metrics at the site level.
Tip: No matter the filters and segments applied to your query, the "Reference" total remains unchanged.
The option "Display context" reflects the global business-oriented information of each item of the analysis. For example: the site selected, the data format (date, integer, decimal, etc.).