Workflow Rule Comparators determine how the Value entered is validated against the property.
The available Comparators will change based on the property selected. For instance on a text property such as Email, you will get text based comparators such as "Contains, Equals, Starts with" etc, allowing you to validate the entered Value against the property in a number of ways.
For example you can set a rule to validate if the email address on the event exactly matches the entered Value, or if the Value matches the start or end of the email address, or matches a part of it etc.
For number based Properties you will get different comparators such as "Between, Greater than, Less than or Equal to", so you can validate the number Value you enter against the number value on the Event, for instance setting this rule to only trigger if the "Post Count on the Support Ticket is Less Than 2" etc.