Not sure about that, but a possibility. I would suspect that ADA makes customs boards for their needs. This said, the board itself is really not where the money goes. It's probably the cheapest component of the whole light. Anyone with some electronic background can make a board and have them printed for pennies. All you need are the gerber files.
In one word, price.
WeekAqua costs around 200-300 USD. ADA is in the 1000 USD realm š¤Æ - I am pretty sure the ADA price incorporates some hefty profit margin and overhead fees but they also probably use better quality LED chips, components and power supply. The PSU that comes with WeekAqua is pretty light and is usually a telltale sign of poor quality. Good quality PSU include higher quality components, like better capacitors, transformers or chokes. These 3 components alone will add considerable weight to the PSU.
Chihiros used to have lower quality PSU in the past and they got so many complaints due to them failing that they changed their PSU to some more reputable brand like GVE and incidentally, they are heavier.