The only real difference between the glass spheres is that the Shrimp Bubble is not a fully-sealed ecosystem. Due to the pursuit of true self-sustainability, we had to deduct points from the rating for not being entirely sealed.
Those are the only points deducted, though. This product hits every other mark: plants AND animals, little-to-no maintenance, and a predicted life of several years.
More importantly, the ability to unseal the Bubble grants the owner the potential to make any necessary changes to ensure the survival of their ecosystem. One could potentially perform occasional water changes to prevent the build-up of toxic waste. Shrimp Bubble even sells shrimp food for the Opae Ula (red volcano shrimp) that inhabit the bubble. While supplementary feeding isn’t necessary, as the shrimp eat the algae that comes with the Shrimp Bubble, it can help maintain health over long periods of time.
Admittedly, this product lacks some of the inherent elegance of the EcoSphere. It isn’t fully enclosed, nor a perfect sphere. The cork may only fit with certain aesthetics.
Note that (a very small amount of) assembly is required. The small jar comes empty. You have to pour the water, shrimp, and algae in separately. This is hardly an imposition, as set up takes less than 5 minutes. Also included is a magnet with which you can clean the inside of the glass while maintaining a seal.
I think this product is an excellent compromise between the pursuit of a truly self-sustaining ecosystem and the humane treatment of shrimp.