MailingLists can be created as "public", using Data Selections and (individually) programmed mail templates to retrieve recipients and mail-content or "private" with a predefined set of recipients with or without Data Selections.
Please be aware, that Data Selections are NOT available in the Admin-Module and that only active users will actually get mails.
Mailing Lists, dependent on (used) Data Selections are not deletable.
Single Mailing Lists can be used to send a mail to every member of the list.
In private lists, members can be deleted and added (either a single member by using the autocomplete-field or a list of selectable members, using the "broker"-functionality)