What is the difference between a task "type" and "category"?
Both enable you to classify tasks. The main difference concern their scope. A task type can only be used for a task while a category can be used for contacts, companies, tasks, projects, notes and documents. For example, you want to launch a news website covering car industry which offers 'news' and 'test drives' in two sections, 'SUVs' and 'convertibles'. You would create two task types: a type called 'News' and a type called 'Test drives'. You would also create two categories: 'SUVs' and 'convertibles'. You could choose to use the two categories for the tasks and the documents. By using it on documents, you could categorize all the market research documents and press releases under SUVs or convertibles.