Difference between "return new Error()" and "throw new Error" in bluebird

returnError.js

var P = require('bluebird');

P.resolve().then(function () {
  // Change this to throw new Error to get the expected behavior
  if (true) return new Error('Returned error');
  return { key: { subKey: 'test' } };
}).then(function (obj) {
  // This will crash if return new Error is used since the Error is not caught by bluebird
  console.log('obj.key.subKey = %s', obj.key.subKey);
}).catch(function (err) {
  console.error(err);
});