We have highleted the different features of the Starter and Extended Packs being offered by Microsoft with the recent release of Dynamics GP 2013. With these packs you also choose between users licensing between Full User and Limited User:
Full User licenses provide users full read and full write capabilities to all of the licensed solution functionality through any and all modes of access, including the Windows Client, the Web Client, the Microsoft SharePoint Client, or any other mode of access going through the API (including Web Services). Full User licenses are for users requiring unlimited read and write access. As long as the number of users needing simultaneous access to the solution does not exceed the number of Full User licenses you have acquired, these users are properly licensed for full read and write access to the complete solution functionality.
Limited User licenses provide users full read but limited yet powerful write capabilities to all of the licensed solution functionality through any and all modes of access including the Windows Client. The Limited User license is designed to give you a lower-cost alternative for extending ERP to users who only need to perform limited tasks as defined in the Microsoft Dynamics ERP Licensing Guide.