If you look it up on Reddit the company is universally hated More on reddit.com

I noticed that Costco had all their Ghostbeds on sale this morning. A lot of people like this bed more than the Casper, and it's cheaper than More on forums.redflagdeals.com

Yeah, the company is apparently kind of terrible, but Costco should be better to deal with. The Ghostbed mattress itself is perfectly fine, unless they've made changes to mattress since I bought mine around 5 or 6 years ago. It's a bit softer than I prefer, but I still think it's a good mattress and I have no complaints about it. It's been used consistently for that entire time (by me for 2-3 years, then by wife since; we sleep in separate rooms due to her night terrors), and it's held up pretty well. If you want something firm, a Ghostbed might not be the best choice, though. Due to the latex, it feels firmer than most other foam mattresses I've had experience with, but it's still fairly middle of the road in that regard; probably slightly on the firm side of medium. It's something that will probably work for most people, and feels firmer than something that uses more memory foam (because there's less sinking), but isn't truly firm. More on reddit.com

Call Ghostbed anonymously and ask but I doubt there is a difference. Plus, Costco return policy is a huge advantage. More on reddit.com