The Dee Ring is very similar in action to the Eggbutt, it will prevent pinching of the lips and gives a slightly more solid feel against the side of the face. It also prevents the bit being pulled through the mouth. The release is slower and some slight poll pressure is introduced.
The Ported Barrel was created to relieve pressure on the tongue via the the medium port, which creates space for the tongue. The Barrel joint relieves pressure on the bars by spreading it over a larger area and limiting the nut cracker action of a conventional snaffle.