Hi,
What is exactly your definition of a "Generic" DataSource? From your questions I derive that you define a Generic DataSource as one that is created using t/code RSO2 in the customer namespace (starting with prefix A* - Z*). Opposite of Generic DataSource is a Business Content DataSource (starting with prefix 0*).
Both DataSources can be found in the same tables (e.g. ROOSOURCE and ROOSFIELD). There is not a single field where you can distinguish between them. The only identifier is the prefix in the technical name: prefix A* - Z* for a custom made (Generic) DataSource and prefix 0* for a Business Content DataSource. For the last category you can also find a DataSource in object version 'D' (delivered).
Best regards,
Sander