Hierarchies in 7.3 IDOC or PSA Mode ?

Hi experts,

I'm trying to implement a Content Datasource for Hierarchies in 7.3.

Working through guidances, there seems to be a difference in

defining mappings in eransformations depending on extraction mode.

My questions : What and where are the criteria for distinction? In Info package, datasource..?

Can I switch it ?

Thanks in advance for your help.

BR

Joe