Very and Useful Article To learn how to compare between AWR With Different Period
Press the Link Here.
Or
1-Use DBMS_WORKLOAD_REPOSITORY.CREATE_BASLELINE_TEMPLATE to instruct Oracle to keep the snapshots for (for example) every Sunday.
2- generate comparison reports with the awrddrpt.sql Comparing any Sunday.
Thank you
Osama Mustafa
Technology Geek 