Data assets in Tableau Data Management are limited to those defined and used within Tableau. Creating a data asset is done by defining a data connection, then choosing tables to use within a Workbook. Once the Workbook’s data asset is complete, it can be published to Tableau Server for sharing and reuse. Tableau does not go out and introspect, catalog, index, and make discoverable data assets outside of Tableau.
Spotlight will introspect and catalog any tables (or files if a file store) within a data connection defined in the Spotlight Server. This makes all assets readily available for use in analysis, regardless if used before in other analytics. Spotlight also makes available any created datasets that combine original tables into an analysis-ready dataset.
Tableau Data Management has varying degrees of data connectivity, depending upon where you are working with the data. There are over 80 connectors from Tableau Desktop, mostly to databases, with a limited number of SaaS applications and cloud services. From Tableau Server, there are 40+ connectors with only one SaaS application. And from Tableau Online, there are only 25 connectors, all only to cloud databases and file stores.
Spotlight lets you connect to and work with far more data, with over 200 connectors to various data sources. The connectors cover a wide range of databases, data warehouses, data lakes, cloud databases and data warehouses, SaaS applications, cloud services, and more.
Lastly, Tableau Server can only integrate (JOIN/UNION) data within a single data connection – it cannot integrate data across different data sources. Spotlight can integrate across any data from any source.