Secondary and more technical, not everything has to or can be real-time rendered, and for that Blender is probably still king of the two, where Unreal Engine is optimized for real-time.
There are things you can only do in Blender, and vice-versa, so what the right tool is will as always depend on the job.
There are other niche tools in a creative pipeline, like Substance Painter for texturing and applying surface shaders. Blender has image and material edition capabilities, but they are more entry-level than competitors to Substance and GIMP/Photoshop.I think there's a niche for a lot more tools, including "AI" stable diffusion-like tools.
Also, blender used to have its own "Blender Game" engine.
As an example, take refraction. I can look up Newton's telescope dimensions, model the lenses in Blender, slap a glass material on there, and look down it to see an accurate view. (Minus diffraction and dispersion, and dispersion can be added manually.)
Real-time raytracing is an answer to this, but it's not quite there in it's current state. It still takes an order of magnitude or two longer to raytrace a frame than to rasterize it, so it's currently only used sparingly to touch up details.
Personally this is one of the areas I'd love to see Blender continue to develop. A spectral rendering option in Cycles would be invaluable when you want to render the Dark Side of the Moon logo.