Is there any difference in these two ways of creating object methods?

Question

Is there any difference in the way these two objects create their methods? Are there performance differences? What's the difference here, if any?

Method 1:

var Point = function(x, y, z) {
    this.x = x;
    this.y = y;
    this.z = z;

    this.add = function(point) {
        this.x += point.x;
        this.y += point.y;
        this.z += point.z;
    };

    this.sub = function(point) {
        this.x -= point.x;
        this.y -= point.y;
        this.z -= point.z;
    };
};

Method 2:

var Point = function(x, y, z) {
    this.x = x;
    this.y = y;
    this.z = z;
};

Point.prototype.add = function(point) {
    this.x += point.x;
    this.y += point.y;
    this.z += point.z;
};

Point.prototype.sub = function(point) {
    this.x -= point.x;
    this.y -= point.y;
    this.z -= point.z;
};