In ADO+, the data set provides disconnected access to database data. In ADO, the record set can provide disconnected access, but is typically used to provide connected access.
There is one significant difference between disconnected processing in ADO and ADO+. In ADO, you communicate with the database by making calls to an OLE DB provider. But in ADO+, you communicate with the database through a DataSetCommand object, which makes calls to an OLE DB provider (or, in some cases, directly to the APIs provided by the DBMS). The important difference is this: you can modify the code of a DataSetCommand object. Thus, you can control how the changes to the data set are transmitted to the database. This means you can optimize for performance, perform data validation checks, or add any other extra processing.