Employee Self Service vs. mySAP HR

What is the difference between Employee Self Service and mySAP.com HR? And how does mySAP.com Workplace fit into the picture?

With ESS it is required to implement mySAP.com for the Workplace component in versions 4.6c and higher. If you have also implemented Payroll, with mySAP.com there may be an additional charge for processing payroll (check with your SAP sales representative).