@tanisha malhotra Confirmation Letter is a communication to tell that the employee has sucessfully completed the probation period.
Confirmation letter communicates - the date of completion of probation, revised designation if any, and if there are any changes in terms of the appointment - if they are not already mentioned in the appointment letter. If the Appointment Letter has already communicated the Changed Terms post confirmation, then no need to mention it again in the Confirmation Letter.
Trust this resolves your query.