Mediation is never binding. It's nothing more than negotiating settlement, except the parties jointly choose a neutral person (sometimes a lawyer, sometimes a retired Judge, sometimes something else) to help the parties settle. The mediator speaks to everyone together, each side can present their arguments if they want (sometimes it's better not to argue and just focus on resolution), and then breaks the parties into separate rooms and speaks to them separately, and then goes back and forth. The neutral gives his/her opinions and usually does it in a way to make each side give up a little more than they wanted for the sake of arriving at a settlement. There's absolutely no obligation to settle. Everything is confidential and not admissible evidence. No decisions are made by the mediator. And you can end it whenever you want. One time I had a mediation last 45 seconds -- needless to say, it didn't settle. Others have lasted several days.
Arbitration is binding, but you either sue in court or in arbitration. It's an alternative to lawsuits in court. And the final arbitration award, once confirmed, has the same effect as a court order/decision and eventually judgment. So if it's in court, it's not going to be arbitrated unless there's a contractual obligation to arbitrate and one party files a motion, in which case the court case is dismissed or stayed and it goes to arbitration.