Some of the columns in Report Writer have ambiguous names and can be hard to know for sure what information is being pulled into the column.
The online help documentation for Report Writer and columns is a good reference. This information is accessible as you create new reports in Report Writer. In step 1, Report Selection, you will see a link for "Learn More". This takes you into the help documentation, where you can then select "Default and Available Columns in This Report". Column names are shown in a table; click the name to see its definition.