Are your Report Builder visit and unique visitor counts higher than what you're seeing in Workspace?
I haven't worked with Report Builder much, but if they're higher, I'd suspect that Report Builder is totaling up the values in each of the breakout lines while by default Workspace deduplicates total values.
For example, if you have one unique visitor who has 3 visits and sees a total of 10 page views. In Workspace if you breakout these metrics by page, you might see something like this
Page. Unique visitor Visits Page views
TOTALS. 1 3 10
Page A 1 1 3
Page B. 1 2 4
Page C 1. 2 3
Overall, there were 3 visits, but adding up the values for each row is higher because more than 1 page was seen on some visits. Same with unique visitor. There's only one total unique visitor, but they viewed 3 pages.
Perhaps report builder might show the totals in this simple scenario as 3 unique visitors and 5 visits, but those are just totaling the values. It's an extra step, if that's the case, but to get the real totals for that period, you'd have to do another query without breaking it out by dimensions that might have overlap.
(You may see similar things on a smaller basis. with time dimensions such as hours, days, weeks, for visits that cross from one to another.)
Hope this helps
