These fields perform different purposes. On the patient we are able to check to see what languages are required, then on the Practitioner we are using it as a search parameter to locate someone who can speak the language, if it's their preferred language is not really relevant. The proficiency in the language is not recorded. There is an extension for modes of communication under HSPC that covers that also (for read/write/speak/listen) There is also a standard extension on patient indicating that they require an interpreter - meaning they do not speak the implied language commonly used in the organization.