Power, it has been explained ad nauseum what the difference is. But as far as I am concerned, it doesn't make a difference. People can pontificate all they want on the merits of the molecule, but, in the end, as I have pointed out, scientists much more knowledgeable than any of us, understanding minutely the MOA, have failed nearly 100% of the time.
Now, there is a group of scientists, besides the Anavex people, who believe there is something to this molecular structure of 2-73 that decidedly needs to be advanced into the CNS field. Anavex has 6 and probably several more who are better than their baselines in the Alzheimer's trial; no other trial has shown one.
So, kld, why not give some credence to the 21st century "Copernicus and Galileo" scientists?