The question reminds me about the other post, where the confusion about what is a Data Source was discussed (and in my opinion not solved). It might be good to remove this confusion in the next version of the Handbook.
For the debate here, it helps consider what the Catalogue WG co-chair Paolo reported in the guideline for registering research product catalogues:
The EOSC Resource Catalogue consumes (aggregates) two types of metadata data sources: (i) research product catalogues and (ii) service catalogues. A data source is a service that offers metadata to the EOSC Resource Catalogue. A research product catalogue (repository, aggregator, etc.) may also be listed as a service through a Node’s service catalogue. This enables users to discover the repository itself as provided by an EOSC Node, and understand its capabilities, access conditions and support.
