Your H: drive is your "home" drive. The W: drive is the "workgroup" area, typically (though not always) used for file sharing with others in your department. H: is considered your private space. Only you have access to it. There you can store work-related data that only you need. For instance, faculty members can store research-related documents, materials that are their "intellectual property" or works in progress that are for "their eyes only." Faculty and staff members may find that we store some types of program settings and information in their H: drive -- e.g., Thunderbird profiles, application configuration files, etc.
A good rule of thumb is that any data that is "departmental" in nature should be stored on W:. Even if you are the only person who works on a particular set of files at the moment, they should be stored on W: if they are important to the functioning of the department and could potentially be needed by others. This helps facilitate the efficient sharing of information through hiring transitions, a leave of abscence and other situations when others may need access to departmental files. If existing folders do not meet your needs, we can create and appropriately secure/restrict access to new folders on W: -- e.g., giving access only to you if necessary.