The writeoffs of student loans actually remove the debt from the accounts of Canada, but that doesn't legally discharge that debt. In the future, the Crown does retain the right to be able to go back and collect or recover the debt. The debt can be reinstated on our books at any time, subject to limitation periods or exceptions that may exist.
Conversely, with forgiveness of a loan, it's actually legally extinguished. It waives the right of the Crown to reinstate that debt in the future and allows both the Crown and the debtor to permanently remove the amount from their books and discharges the liability.