__proto__ vs prototype

The __proto__ property of Object.prototype is an accessor property (a getter function and a setter function) that exposes the internal [[Prototype]] (either an object or null) of the object through which it is accessed.

__proto__ is the actual object that is used in the lookup chain to resolve methods, etc. prototype is the object that is used to build __proto__ when you create an object with new:

_proto_

var parent = {

  color : 'white'

}

var child = {}

child  = Object.create(parent)

child.color //White

parent.color = 'black'

child.color  // 'black' because of _proto_ chain

Prototype

function Soldier() {}
Soldier.prototype = {
  weapons: ['rifle', 'grenade', 'bayonet'],
  weaponOfChoice: 'rifle'};

var GIJoe = new Soldier();
var Rambo = new Soldier();

Rambo.weaponOfChoice = 'compound bow';
Rambo.weapons.push(Rambo.weaponOfChoice);

console.log(GIJoe.weaponOfChoice);   //because of prototype value not changed
// > rifle
console.log(GIJoe.weapons);