What's the Difference between Regular Method & Setter Method?

Hi, sorry, maybe this is a stupid question, but I’m still curious. What’s the difference between setters and regular methods? Because I tried to use regular methods to replace the setters and the result was the same.
Thank you in advance.

const robot = {
  _model: '1E78V2',
  _energyLevel: 100,
  _numOfSensors: 15,
  get numOfSensors(){
    if(typeof this._numOfSensors === 'number'){
      return this._numOfSensors;
    } else {
      return 'Sensors are currently down.'
    }
  },
  numOfSensors(num) {
    if(typeof num === 'number' && num >= 0) {
      this._numOfSensors = num;
    } else {
      console.log('Pass in a number that is greater than or equal to 0');
    }
  }
};

robot.numOfSensors = 100;
console.log(robot.numOfSensors); // 100

as mentioned in these docs:

The get syntax binds an object property to a function that will be called when that property is looked up.

so the same goes for a setter, the setter will be called when we use assignment on that property:

robot.numOfSensors = 100; // will trigger setter

calling a method is different from assignment.

the advantage of getters and setters is that we can specify behavior for a property