Arbitration is a binding process where a third party considers the evidence and law and makes decision as to whether money or other relief should be awarded to one party or the other. It is similar to litigating a dispute in court, except that arbitrations are generally conducted in private. Arbitrators (the individual(s) deciding the matter) are not publicly appointed or elected judges. Instead arbitrators can be lawyers in private practice or retired judges (or in some cases, non-lawyers).
Mediation is a non-binding process, meaning that no party is obligated to come to any agreement. Rather, the mediator attempts to get the parties to come to an agreement for resolving the dispute.
A settlement conference usually refers to an “off-the-record” meeting with a Judge in a pending lawsuit. The Judge (who may or may not be the same one overseeing the case) attempts to get the parties to come to an agreement for resolving the dispute.