Explain the difference between .twb and .twbx

A .twb is an XML file describing the workbook — which fields sit on which shelves, how things are formatted, where the data lives. It contains no data at all. Open one on a machine that cannot reach the source and you get the layout with nothing in it.

A .twbx is a packaged workbook: a zip holding the .twb together with a copy of the data extract and any local resources such as background images or custom shapes.

The practical rule is that .twb suits people inside your network who can reach the same database, and .twbx is what you send to someone outside it. A .twbx is also what Tableau Reader opens.

Because it carries data, a packaged workbook is much larger — and worth thinking about before emailing it, since anyone who receives it has the underlying rows.