These terms as they are used on this site are almost but not quite synonyms in English. A site user can also be called a site member but membership implies a little more than the word user. For example there are lots of people who use this site but have never registered on this site so they are users but not members. A user who registers on the site becomes a member but it is not wrong to say also he is a user. So in English "Member List" is a better term for the list of registered users, but still "Manage User" is a more natural expression than "Manage Member" when we speak of the administrators ability to edit user properties.

Hope it helps,

Joe