Global report suites can aggregate data from multiple report suites into one high-level report. This allows you to view data from multiple report suites at once, enabling you to quickly compare performance across sites, countries, or other groupings. Additionally, global report suites can aggregate historical data, allowing you to see the overall performance of a site over a period of time.

Rollups, on the other hand, are used to aggregate data from multiple report suites into one report suite. This allows you to view data from multiple report suites at once, but it only reports data from the point they were implemented. As a result, rollups cannot be used to view historical data, as they will only report data from the point they were implemented. Additionally, rollups are only processed at midnight each night, while global report suites report data with standard latency.