You are thinking in the right direction.
Based on direct comparison between the 2 singlets in my hands, both uses same material, with slightly different openings positions and cutting. Functionally, they are pretty much the same product. My understanding is NEDAO buys from factory with its own specifications and marks up the price, while the factory sells it without any labels, different cutting, different opening, different seam treatments, etc. As you described, they feel the same, then its the same case as what you have experienced.
With regards to the issue of fabric quality, I have my own share of experients gone south. Having bought some of the cheapest found in 闲鱼 when i first started running, i have acquired quite a bit of lousy fabric running gears. Better fabric does feel softer, lighter to my skin. Even when i perspire tonnes and tonnes, while it sticks onto my body, they still feel nicer/better than lousier ones. One positive example I have is a runner top by QinKung, which I bought from its official 小红书 account. XHS link below for reference
https://xhslink.com/m/3Ms2YBABXii
However, this is really trial by error and personal liking/sensitivity. One has to pay some school fees to establish personal preferences/liking and both positive and negative examples before knowing what to look out for.