Difference between Marketing lists and Segments?

Hi all,

Im wondering what the difference is between marketing lists and segments are and what & when to use either of them.

Since all mailings and customer journeys are started from a Segment, then what are the use of marketing lists?

I want a way for salespeople to add certain contacts to marketing lists, which they can do from the Sales app, but when in the marketing app marketing lists seems to have a minor role?