In general vendor supplied IDTs are simply a CTL implementation of the maths from their published white papers. They are not different.
In theory an IDT could incorporate an exposure offset to standardise exposure between cameras from different manufacturers, as there is a degree of choice in the placement of mid grey in the manufacturers’ log encodings. However I am not aware of any published IDT where this has been done.
The IDT documentation describes the process for creating a transform from raw sensor RGB to ACES, and this necessitates use of a different matrix for different illuminants. However in most use cases the IDT is transforming not from sensor native but from a manufacturer’s encoding of the sensor data, such as ARRI LogC3. In this case an illuminant specific matrix has already been applied as part of the encoding, so only one IDT is needed to transform to ACES.
The only real variation is in the choice of Chromatic Adaptation Transform. Manufacturers usually use the same CAT for matrices in their white papers and published IDTs. This has been discussed in detail in another thread, but allowing manufacturers a free choice of CAT means that there is a small difference between the result of going e.g. directly from ARRI Wide Gamut 3 to RED Wide Gamut, and going AWG3 → AP0 → RWG, because both camera spaces use D65, so no CAT is needed for a direct conversion, but going to ACES and back uses a different CAT in each direction.