MEAN stack is a full JavaScript solution that helps you build fast, robust and maintainable production web applications using MongoDB, ExpressJS, AngularJS and Node.js.
Sails.js allows you to build custom, enterprise-grade Node.js apps using the Model-View-Controller pattern to organize your code so it is easier to maintain.
New MEAN Stack = MongoDB+ExpressJS+AngularJS+Node.js+Sails.js = MEANS stack