OLEDB vs ODBC to access postgres

I am using a grid component (delphi) connected via Postgres ODBC , and
via Datasource - ADOTable - ADOConnection to a postgres database.
All works well.
Tried using the PostgreSQL Native Provider, built a working
connection string.
It connects OK but I have only read access to the data (in the grid I
cannot edit or add any rows).
I have also tried several other OLEDB providers but they all exhibit
the same behaviour.

Why does ODBC work and PostgreSQL Native Provider (or other OLEDB's)
not work?

Help would be appreciated on this as I have spent a long time
researching what to use for my future commercial projects.