Not sure where to put this, but a new video is out! They've got some new details about the giants! I'm very excited to learn more about the Unfallen Fomorians, among many others!
I think the difference between giant scions and empyreans is a matter of planar alignment.
They're both essentially demigods, the children of the divine, but empyreans are classified as celestials (titans), implying a stronger connection to the Outer Planes.
Giant scions, by contrast, seem to be framed as more elemental in nature, implying a connection to the Inner Planes, similar to the 4e's take on titans as primordial elemental giant precursors. Alternatively, if they're trying to parallel them with Fizban-style dragon greatwyrms, possibly linked strictly to the Material Plane itself.
So similar concept, but different cosmological "teams".
Well, let's wait to see the new Giantish take on the First World mythos here. The Giant gods appear to be tirs to Dinosaurs and Loat World stuff, too, and the Elemental aspect brings to.mind the Primordials of the Dawn War...They are both descended from Gods, which implies a link to the Outer planes inheriantly.
Yeah, remember also that with Fizban’s, Tiamat and Bahamut were not even considered gods in the tradiational sense according to the First World Mythos, and acted more like the primordials in that they created the actual material plane. They became tied to Avernus and Celestia after the fact.Well, let's wait to see the new Giantish take on the First World mythos here. The Giant gods appear to be tirs to Dinosaurs and Loat World stuff, too, and the Elemental aspect brings to.mind the Primordials of the Dawn War...

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.