The process and results of a lawsuit are public information, and open to public disclosure. Negotiation is private and only known about by others if the parties disclose information themselves. Mediation is a confidential process, the details of which are not discoverable later in court. An agreement arrived at in mediation, if it is filed in court, is public information, but the agreement does not include the details of the discussion. Mediators have an ethical responsibility to maintain confidentiality.
Arbitration is confidential to the extent that the parties structure it is as such.
In both mediation and arbitration, all parties are expected to keep any of the discussions confidential. In a public courtroom, no one is asked to observe confidentiality. Litigants commonly talk about how much they have come to despise each other in the process. The conflict has only escalated during the process of preparing for trial, and people often think they have too much invested in the trial to consider the option of turning back. At this point, relationships may be so damaged that they are irreparable.