Any user, regardless of customer or agent, can filter tickets using custom filters if default filters are insufficient. For example, if the user wants to see all tickets of category Marketing and priority High.
The limitation of the custom filter is that it is one-time. Therefore, if you need the same filters repeatedly, you must follow the procedure of adding custom filters every time.
Saved filters solve this case by enabling users to save the filter with a custom name/label so they can use it in just one click next time.
The difference between default and saved filters is that the administrator sets the default filter, and it is available to all users. In contrast, the saved filter is set by the user and available only to him.
Users can add, edit or delete their saved filters.