Hi Aravind,
Basically STAD will delivers you workload statistics across business transactions.
It will give you transaction started time, server that it executed, transaction , program name, response time, wait time, cpu time etc.
By double clicking on the relevant entry you can explore more details regarding that record.
This article may be helpful for you.
http://www.sap-perf.ca/run-sap-stad/
Depending on the requirement , you can perform the analysis.
(example - what are the programs that taking more DB time. what are the most frequently used t-codes, From which terminals users are accessing etc)
STAD will provide you only the statistical records based on user,transaction. By default it will available for 2 days data (48 hrs)
whereas ST03N allows to get details like workload analysis, performance of database,load distribution. You may check that as well
regards,
Zerandib