I'd say their features should be about the same, the Dark Matter is just a recolor of the complete Amazing Exia with a few different weapons and tuned to the Totally Not Cyber Newtype system. Oh and a faceplate too. The Exia Dark Matter foregoes the Amazing Exia's GN Shield on the left arm and the large GN Sword on the right in favor of focusing on the fire and ice handheld blades for melee combat. The Amazing Exia keeps its shield on the left and has an Exia-style large sword mounted on a small shield on its right, while also carrying a handheld blade which might not freeze on contact, it doesn't sound like the Meijin's style. That's really all the differences between them.
They both have the same miniature rifle mounted on a small shield, Exia style, that can be used as both a beam saber or a beam gun, they both have GN vulcans on their wrists, a bird-like booster used to enhance speed and mobility that can detach and operate independently and is armed with a beam gun on its "head" for that purpose, solid tonfa-style blades on the booster's wings. The only other things I'm not sure the Amazing Exia can do that the Dark Matter can are generate beam sabers from its wrist-mounted vulcans and create a GN field when the booster is attached. But going by them being seriously the exact same model sans the differences I listed, I'd say yes.
This is all up for vance to call, obviously, but there's fairly good evidence pointing towards their features being exactly alike save for the few weapon differences and the Embody system. Performance-wise they should both be about equally powerful too, the base model was developed by the people behind the entirety of the Gunpla Battle tech and the complete version was custom-made for Tatsuya's style by both himself and Alan.