I can’t speak for the Signia/Rexton rebrand, but I’d imagine that it’s similar to the Phonak/Kirkland Signature rebrand, in which case it’s true that the core technology is identical, except that Costco wouldn’t enable the tinnitus function for their KS branding. The reason that makes this most obvious is that the same Phonak Target software can be used to program the KS series’ counterparts of the Phonak rebranded models.
But it’s not obvious like that with William Demant HAs. The first telltale sign that it’s not a simple rebrand is because they all keep their original company brands when they’re sold at Costco. Bernafon is still Bernafon at Costco, Philips is still Philips at Costco, unlike Phonak models became KSxx models, and Signia models become Rexton models.
Secondly, Bernafon has its own programming software that looks and feels different than the Philips software that looks and feels different than the Oticon software, unlike the Phonak Target software that can be used for either the Phonak models or the KSxx models. I’m not familiar enough with the Signia/Rexton rebrand to say that they share the same programming software or not here.
In terms of “significant functional” differences you’re asking about, I would separate the functionalities into 2 categories, the functionalities of the core technology, and the functionalities of what I call the “peripheral” technologies.
The peripheral technologies are things like the charger, the streaming device, the frequency lowering technology, the feedback management technology, the Near Field Magnetic Induction technology for binaural communication between the left and right aid, the sudden sound stabilizer technology, the wind handling technology, the new built-in Music program construction, etc. It’s pretty obvious that at least between the Philips and the Oticon models, they share many of these technologies.
However, the core technology of the latest Oticon models is the Deep Neural Network (DNN) AI engine, and while the core technology of the Philips models is also AI based, its description does not seem to be the same as the Oticon DNN technology, but it’s an AI technology that focuses more exclusively on noise reduction. I’m not talking about them having simply naming differences here. If you read the whitepapers describing the Oticon DNN and the Philips AI core technologies, they went about explaining the detailed architecture and operations of their core technologies, and it’s obvious when you read these whitepapers that the 2 operations are entirely different.