We use IPDS and IAPA. Eventually we will be using TARGETS for everything.
We are speaking the same thing.
The difference here is that IPDS is simply the FAA's acronym Instrument Procedure Design System, but its parts are supplied by a 3rd party contractor. Just as TARGETS is supplied by MITRE. Instrument Approach Procedure Automation (IAPA) is the old version of the system being replaced by IPDS.
I was working with ATSI when the FAA was using SAAR-Pro (I called it RNP-Pro) to design and validate RNP-AR procedures, and helping with the data port to TARGETS. Check with the guys at AFS-460/420 for how they use RNAV-Pro and SAAR-Pro..
That is why the FAA requires operators to use RNAV-Pro, because in reality, that is IPDS and already part of TARGETS.
This is TARGETS:
Data file exchange is supported between TARGETS and the Total Airspace and Airport Modeler (TAAMŽ), the Sector Design and Analysis Tool (SDAT), RNAV Pro™, and MapInfoŽ
While MITRE has the development contract for TARGETS, MDA had the development contract for IPDS (although I am not certain they still have that)