1. In Designer level filters means U can restrict data from
the Data sources.
  But Report Level after fetching the full data then we can
apply filter on that data.

2. after u can developed universe u can export development
domain and share Ur developed universe.

3.In BO 6.5 U can using supervisor to set particular group
access to particular reports.

1)created filter in designer level to restrict the data 
from universe level 
   
    using filter in report level filtered the data in report
 EX :if u want a report in delhi based customers that kind 
of situvation using filter in report level

2)in universe developed it will import in client machine 
for the client format requirements

3)in earlier version of business objects 5.0,6.5 the 
supervisor give the access the report,in BOXI the developer 
will give the report level permissions