On a light table it's immediately obvious what is Portra 160/400/800 and what is Gold 200 simply from the mask colour. And, just as Kodak states in the data, the visually apparent granularity of Gold 200 is about level with Portra 800 - and that's before getting on to the colour rendering differences - and that Gold's colour repro latitude is wider but less realistic (i.e. a more idealistic memory) - which may well be playing a role in why people want to claim it is 'better' than more accurate films like Portra. Either way, I think it's a useful expressive material to have available.
Mostly this, I still haven't taken the chance to try Gold in 120 (only in 35mm) because I have been able to stock up on Portra 160 at about the same price level
Kyle McDougall makes a comparison, which I would say is practically useful for most users (lab scan, etc). The largest difference IIRC (saw the video a while ago) is grain. P400 is quite finer. Otherwise color+contrast difference and a tiny bit more halation in specular highlights for Gold.
Count on that negative films nowadays rely a lot on inversion and postprocessing, making it possible for different films to look similar.
It's quite possible that components are shared with the Portra line, but something is changed for the difference in price and performance. Even PE mentioned that changing base material required non trivial changes.