Begginer, API vs XBeeConfigBlockDDOfunction

a little bit confused from the connection of phyton XBeeConfigBlockDDOfunction and API. Are those the same?

the XBeeXBee-PRO ZB RF Modules speak about API
but in the code it is used by XBeeConfigBlockDDOfunction

so are those the same, XBeeConfigBlockDDOfunction is a functionrunning the API?
any document for that?

I think this page might be of interest to you: