They’re not the same.
Imaging is precision. That violin is right there, not two inches left or right. The voice stays put, locked in space.
Soundstage is size. Width. Depth. Air. The feeling of the room.
You can have one without the other. A system can image like a laser but feel small. Or it can be big and lush, but blurry.
The magic happens when you get both. That takes phase coherence and mostly, proper setup.
Too often, I hear folks getting the one right without the other. Pinpoint accuracy without the big picture.
Get them both right and bingo!
It's what we all hope for.