They are not the same skeleton, rig, or animations.
Here is the female dreadlord model (Dreadqueen.m2) and Incubus model lined up
(Video)
https://puu.sh/IYVnT/de42f29b2d.mp4
(Picture)
It's
super easy to line them up,
because they use the same rig, you can just make them the same size, line up the feet and knees and everything else lines up nearly exact (slight differences in animation cycle aside) because they are two models on the same rig. This is what two models that use the same rig look like. The are proportionally 1:1, because if they are not the same proportionally, the rig does not line up with various joins and moving parts that need to move, and the model will bend in weird places.
Here is the female dreadlord model and the Dracthyr model "lined up".
(Video)
https://puu.sh/IYVsy/b25ff46c4a.mp4
(Picture)
I put "lined up" in quotes, because you can't actually line them up, because they use two entire different rigs with totally different proportions. I lined up the feet and knees where they should be matched, as above, and nothing else matches or lines up because they aren't the same thing, or even close to the same rig. All that is similar about them is that they have the same digitigrade legs. Note that to even attempt to make the feet and knees line up, you have to size the Dracthyr much smaller, because it's a very tall model, where the Incubus/Dreadqueen are squat.
To drive home the point,
https://puu.sh/IYVx8/4aaecd108c.mp4
here is a 90 second video of me lining up all three, so you can see how easy it is to line up the Dreadqueen and Incubus, because they share a rig, and how you literally cannot line up the Dracthyr, because it has a totally different rig with wildly different proportions, so the legs do not line up, and to get them to even be close you have to have the Dracthyr's shoulder way up where the head should be on the other rig.
I don't even understand how this is a conversation that's happening beyond people taking Ercarp's totally flawed original comparison of "they look like they have the same pose at this one frame of their running animation" and running with it.
You can see at a glance that they are not the same rig, the Incubus/Dreadqueen rig has arms so long that their hands are at their knee and the wrist is below their butt, where the Dracthyr has normal humanoid proportions
