Is there any difference between P and Y I/O packs in the MarkVIe Control System?

Basically the title,it seems like every I/O pack that is connected to the MarkVies Control System is the same as the one connected to the MarkVIe Control System except the reliability of the I/O pack.So what is unclear to me is there any difference on what they do?of course if I have connected different signals to them they are going to measure different values but lets say I have connected the same ones,is there going to be any difference,or is there any difference except the reliability between YPRO and PPRO?
Well. the BASIC difference is thousands of US dollars in price...!

It was my understanding that, in fact, there are some subtle--but important, even critical--differences in the firmware of the non-SIL and SIL I/O packs. I think I've even seen some different configuration options in ToolboxST between similar packs (such as YPRO and PPRO).

One of the ways that reliability of electronic assemblies--made up of discrete electrical components (resistors; capacitors; op amps; chips of various types; optical isolators; etc.)--is enhanced is by using components with quite tight tolerances and made of high quality materials. (Think of resistors with a 1% tolerance versus a 5%- or 10% tolerance, for example--usually visually they appear to be of a higher quality, and certainly, the price is higher.)

Whether or not the actual physical printed circuit assemblies differ much--other than the quality of the discrete components--for pack of the same function (again, such as YPROs and PPROs) is not known, but my suspicion is that they differ very little, if at all.

Personally, I wouldn't try substituting a PAIC for a YAIC, or vice versa (a YAIC for a PAIC), especially in a TMR or even a DUAL reduandat Mark* VIe/es application. I think that would require changing the I/O Pack type and downloading PCODE (basically firmware) to it, and if it's "mate(s)" weren't also changed to match I think that might create some issues. (I seem to recall reading somewhere once that SIL-rated I/O Packs might even operate at a faster rate for some functions (say, speed/frequency sensing, or some particular A-to-D conversions), which could introduce some unanticipated and unusual knock-on issues. I certainly wouldn't try replacing a YPRO with a PPRO, and probably wouldn't replace a PPRO with a YPRO, either--since these are very critical I/O packs.

But, I am a much more conservative engineer than many, so make what you will of the above paragraph.