Hi Cleo,
Let me try to clarify your doubt...
Before getting into the details lets try to understand the reason for developing this new feature called as Operational Data Provisioning (ODP).
Earlier if user wants to extract data from SAPI or DB connect or via Data service we used different interfaces. But SAP wanted to have only one interface for data extraction and the solution for the same is ODP. So in BW on HANA system with ODP context user can do
1) SAPI extraction
2) BW extraction
3) Extraction using Data service
4) SLT and etc........
And one big advantage of using ODP context source system is PSA data is not mandatory .ODP provides ODQ(Operational Delta Queue) which will maintain the delta information. So in BW on HANA system in RSA1 transaction under source system you will find normal source systems along with ODP type source systems.
To answer your last question, ODP will handle delta as mentioned earlier. So SLT will push data to ODQ then you can extract to PSA or directly to your provider. Its not mandatory to use only ODP context data sources always but for newly creating DS its advised use this because of optional PSA advantage....
hope this clarifies....
Thanks & Regards
A.Dinesh