Nope. I suggest you read the BRZ brochures. Between the Premium and the Limited the suspension tuning are identical. The Limited comes with the 7.5 X 18 inch wheels and the Michelin Pilot Sport 4 tires. the Cheaper Premium comes with 7.5 X 17 inch wheels and the Michelin Primacy tires. This is exactly the same on the GR86 side between the base GR86 and the Premium GR86. However, there are suspension tuning differences between the GR86 and the Subaru BRZ. Perhaps that is where you are seeing the suspension differences.
Yes, correct but these have nothing to do with the original question about suspension that RylisPro brought up. You get all these goodies in the interior with the GR86 Premium the same as you get the BRZ Limited(with the exception of the extra duck spoiler). However, as I mentioned before there are NO suspension upgrades between the base GR 86 and GR86 Premium just as there are NO suspension upgrades between the Premium BRZ and the Limited BRZ. The one difference that exists in both models are larger wheels and tires on the GR86 Premium and BRZ Limited. As I said previously there are suspension tuning differences between Subaru and Toyota as far as the BRZ and GR86 but no suspension upgrades for the most expensive models.