Every contact record has a field for "Origin Application Type" which specifies the type of action they took that added them to your site. The best way to group constituents based on this information is with a query:
  1. Go to Data Management > Query
  2. Click on "Create a New Query"
  3. Give the query a name and description, click "Save"
  4. Choose "System" for the field type and then "Origin Application Type" for the Field, then click on "Add Field Clause"
  5. Here you will be given a pop-up window where you can choose which application type to filter with. You can use the logical operators in the query tool for more sophisticated filtering