Is it possible to configure backup filename conventions for Maintenance Plan Wizard in SSMS Is there a way to configure SSMS so that the backup file names for differential backups (created using the Maintenance Plan Wizard) would have the string  "DIFF" in the name?
I would recommend using Ola's scripts.

https://ola.hallengren.com/sql-server-backup.html

Not only are they awesome but they will give you the naming convention that you are looking for.