I wonder how this is different from Bryce, also can .obj from Blender be imported into a scene?

I'm not familiar with Bryce. There are plenty of external terrain programs that can work fine with Unity, you just need to import the raw heightmap file or use a FBX/OBJ file. Yes you can import stuff created in Blender including the .blend, FBX, and OBJ files. I typically use FBX.

Thank you for your reply.