The Sony X90J is the Sony X900H's successor. They're very similar overall, but there are a few differences. Although both TVs use a VA panel, the X90J has a higher contrast ratio, which means it can display deeper blacks. Its color gamut isn't as good as the X900H's, but it gets significantly brighter in HDR to make highlights pop, and its brightness is more consistent due to a less aggressive Automatic Brightness Limiter (ABL).
Source: https://www.rtings.com/tv/tools/compare/sony-x900h-vs-sony-x…
Sony is now price matching the Costco deal, which means you can get the X90J with free delivery and a bonus remote for $1978.99.Cashrewards had 6% cash back the other day, but that appears to have gone down to 2% - still much better than this deal though.