Are Rollei IR400, Retro 400 and Superpan 200 really the same thing in different packaging?
The general consensus is that yes, they are the same film. All are differently confectioned versions of the same source film, Agfa Aviphot Pan 200 (original data sheet
here). A number of other, non-Rollei-branded films are also reportedly derived from Aviphot Pan 200, including JCH Streetpan and Catlabs 320.
The same is true of Rollei Retro 80S and Rollei RPX 25, which are sourced from Agfa Aviphot Pan 80 (original data sheet
here). At least with regard to Retro 80S and RPX 25, I've shot a lot of that stuff in 120 (both films) and 4x5 (RPX 25) and can confirm from personal experience that they are indistinguishable from each other. Rumor also has it that Adox HR-50 is a pre-flashed (and hence, technically modified) version of Aviphot Pan 80.
Repackaging the same film into different brands, names, and EI values seems a bit deceptive at first, but when you consider that a single film can achieve different looks through different exposure and development techniques, it's perfectly fair. For example, at box speed and development, Retro 80S gives a high-contrast image, whereas the same film treated as RPX 25 gives a more normal, pictorial contrast through what is essentially a pull in exposure and development (i.e., over-expose and under-develop).
All that said, it's important to note that not all companies have the same quality control. Rollei Retro 80S and RPX 25 are both available in 120, but you'd do well to stay away from the Retro 80S in that size and go with the RPX 25. Retro 80S is confectioned somewhere in continental Europe (Maco, Foma... not sure who or where) and has had a mutli-year-long problem with mottling caused by inks on the backing paper interacting with the film (I've gotten bad rolls of this stuff almost every year since 2019). By comparison, the RPX 25 version is confectioned by Harman in the U.K. and has had no such problems that I've personally seen. The 135 versions exhibit no such problems because they have no backing paper. If you want to shoot this film in 4x5, RPX 25 is the only "label" available in that size.