An Actuate Group Section will group similar records 
together by a key field. A query pulling all the records 
from a table with 100 records and grouping by State or 
Province will still display 100 records on the report. No 
data is lost or aggregated.

A SQL Group By will aggregate data being pulled from a 
table. Grouping By State or Province will result in 
somewhere less than 100 records being delivered to the 
report. The results most likely will be 5 records 
containing a count and the state name: DL-20; MH-10; BR-5, 
WB-25, and MP-40. A Group By processes the data and creates 
new information about that original data.

Using the Group by in the SQL returns the data form the 
database which is grouped by that attribute. 
If u r not grouping through the SQL if u wan to group in 
thr report from the front end through actuate, u can use 
the Group section.