The main difference between Adjustments and Write Off's is whether the user is trying to change information on a gift that has been posted (adjustments)or trying to write off or remove part of a pledge or pledge payment(write off's).

Pledges and pledge payments can be written-off at anytime when the pledge is no longer valid or if a constituent is unable to make their installment/payment. Only the gift types of pledge and pay-cash can be written off. All gift types can be adjusted but it is only necessary to adjust a gift if the Post Status of that gift is marked as Posted (meaning it has been transferred/posted to your account software-usually Financial Edge/General Ledger).

When the user adjusts a gift the user can change the gift date, the amount, the fund, the gift subtype, and the post date and post status of the gift.
The user can also Adjust a pledge to change the installment schedule if payments have been made against the pledge and you need to add or subtract installments in your installment schedule.Adjusting a gift allows the gift to be posted to the Financial Edge/General Ledger program again with the proper information.
The only other way to change pledges is to delete the pledge and/or pledge installments and reenter the information correctly. The user can also delete other gift types and reenter them as well instead of adjusting the gift.