Yes, Mods's job is to deal with the players. but people are generally too fucking retarded to notice this so at the tiniest thing that goes awry. "ADMIN!!!!!!"
Yes, Meds's job is to deal with the hackers/spammers. but people are generally too fucking retarded to notice this so at the tiniest thing that goes awry. "MODERATOR!!!!!!"
Ive very, very, VERY rarely seen someone ever scream "MODERATOR!!!!!"
Mediators's job is to welcome new people to the server, and in the case that other staff is offline, investigate into critical player issues. and to sometimes work out small squabbles that a Mod cant be bothered into doing.
TL;DR- Mediators are the unpaid interns of staff ^_^