Bloomerang has 5 different data types throughout:
When creating reports you need to decide which type of data and need to see in the display, and what you want your rows to be in your report results. This is where the report data types come in.
When you create a constituent report you can filter by and display in columns constituent profile data, and you can also see certain aggregate data of other types. Each row in your report will correspond to a separate constituent account.
When you create a transaction report, you can filter by and display in columns transaction AND constituent data. Each row in your report will correspond to a separate transaction
The same goes for Interactions, notes, and tasks.