What are the differences between twb and twbx?

A .twb holds the workbook definition only — sheets, dashboards, formatting, calculations and the connection details. No data travels with it.

A .twbx is that same file zipped together with a copy of the data and any local resources such as images or custom shapes.

The consequences are practical. A .twb is small and stays current, because it reads live from the source every time — but it is useless to anyone who cannot reach that source. A .twbx opens anywhere, including in the free Tableau Reader, at the cost of being larger and frozen at the moment it was saved.

Worth remembering that a packaged workbook hands over the underlying rows to whoever receives it, which is a data-governance question as much as a file-format one.