CRM Lead Filter is used to filter the leads against leads directly. However, multiple approved CRM Lead Filter can be used in the canvas while creating routing territory.
Every possible variation can be filtered and matched in Smart Lead Attributes.
CRM Lead Filter is defined based on the list of attributes that are returned from the CRM for the particular lead and contacts. All the attributes available in the CRM or SalesForce are available as filters. You can use the default filters or customize filters to define how the filters are combined.