Kindly advise on having adjusting periods. How different it's from normal period?

As far as I know before you process year-end closing journals, you should:
• Set up the last day of the fiscal year as an adjusting period.
• Set up the first day of the new fiscal year as an adjusting period.


Thanks and Regards,
Shanmuga

These are not hard and fast rules. Most companies do not use adjusting period. Some companies use 1 adjusting period and few uses 2.
From technical side the only thing you should keep in mind is that adjusting periods would overlap with regular periods. For example DEC-10 would span from 01-DEC-10 to 31-DEC-10 while ADJ-10 would consist of only 1 day (spanning from 31-DEC-01 to 31-DEC-01).
You can put last day of the year in one adjusting period and first day of the year in another.
Keep in mind that this in not your decisions. Accounting Department would decide. You would implement business requirements.