I think that the differences are in the tuning choices, the bass texture (the drivers technicalities), the AMTS deployment and its effect on both sound signature fit-dependant variations and mid to high frequency uniquely exquisite clarity, the fit/clamp/seal/passive isolation differences, induced partly by pads depht differences.
The Stealth drivers are technically superior, I think, to the E3 drivers. E3 drivers are based on the flagship drivers but "downgraded" ? Built to a price target, according to Dan. I don't remember if they implemented new developments in the E3 drivers. Maybe someone knows.
But then on the other hand, AMTS progressed quite a bit with Corina, and Dan implemented the AMTS in a novel way with the E3.
I think the distortion in the bass is the biggest difference between the two, for me. And I kinda get the feeling the Stealth has quicker ballistics down low too. It really makes a difference in the perception of bass. I found the Stealth sound and E3 sound to be quite different... I loved both... The E3 fit/clamp/seal on my head was so much better that it won without question & I bought the E3. But you know, I still think the E3 has a bit too much bass, bass that blossom a bit too much, and bass that lingers a bit too much maybe ?... And I got these feelings right from the beginning, listening to the first song of the playlist, Massive Attack - Angel. But these big words I use are just vehicules to express what I heard, please don't think these audio nuances are deal breakers because it's all quite subtle... Also, the E3 kind of "rich", "bloomy", "driven", "loaded" bass could just be your thing... For context, me I try to get as close as possible to the bass I hear on my studio monitors, where it's quick, responsive, elastic. I need to design my kicks for example, so I need all the details I can get. If the bass is blurry, driven (even slightly), then it's complicated to make informed decisions.
DCA are sending me a set of longer screws and little plates to change the HPs clamp. ASAP, I'll get a Stealth in the studio to experiment.
I can't get the Stealth sound out of my head. It was I.N.C.R.E.D.I.B.L.E. I can't even imagine how the Corina sounds... But whatever happens, my E3 is going nowhere ! It's a great entertainer !