Is an email segment or an email list the right choice?

We're big MailChimp fans at T&S, so we tend to use the same language they use. As they define it in the MailChimp glossary, a list is "a collection of subscribers who have opted-in to receive correspondence from you or your organization." A segment, however is a subset of that list. MailChimp defines it as, "a section of your list that includes only those subscribers who share common field information."