I spent a lot of time talking with Douglas before I purchased the aluminum chucks. I think that he would say that the difference is the "angel wings" that are used in the Odd-Not vacuum chucks. I have a single 5 inch Oneway vacuum chuck and whether I am using the Oneway stick on pads or a Rubber Chucky ring I have had a problem losing vacuum and his pitch is that the angel wing helps maintain the seal. At one point he mentioned that he gets regular requests to produce angel wings for Oneway vacuum chucks. Here is the description from the website.
https://www.odd-not.com/shop/p/angel-wing-seals
"Put a
Angel Wing Seal on the shoulder of your vacuum cup and receive forgiveness that you’ve never seen in any-other vacuum chuck system. Forgives equals resilience. The other systems all share one similarity, despite how different from one another they look. What they all share in common is if there is
any separation /
a gap formed between your bowl and the cup the vacuum is lost and so is the hold on your bowl. That gap can come from a sudden catch that the other systems never recover from. Angel Wing Seals allow .50” (1/2”) or more gapping between bowl and cup before completely letting go. In plain English: if you pull hard enough you will overcome the force of the vacuum pressure but if the pulling force is released the bowl / vacuum holding will recover pulling the bowl back to the cup. The bowl will likely not be back on center but your bowl will not be on the floor in pieces. All is not lost. Release the vacuum, re-center the bowl on the chuck and turn the vacuum back on so you can continue to finish your work."