Here's a side-by-side comparison of the ADA Aqua Design Amano 20C Garden Cube Tank versus the UNS Ultum Nature Systems 20C Cube Tank. Both are low-iron and have nearly flawless corners and edges.

One immediate difference you can see is that the ADA tank is thicker and appears to have a lot less iron in their glass and this can be seen simply at the corners and edges of the tank.  Both use very low-iron glass with German grade silicone and are nearly flawless in terms of their craftsmanship.  

Another difference is the overall bevel of the tanks.  UNS is the only tank on the rimless aquarium market that has the 45 degree bevel and this gives an overall flush and clean look to the tank whereas ADA's is just the standard bevel though it's still very clean and uniform all around.  

One thing about the UNS tank is it has a laser etched logo on the bottom right corner while the ADA tank is simply a sticker attached onto the tank.  

Side-by-side, they are both gorgeous and immaculateless.  

We've used both at our store and can say they are both great for aquascaping projects!