Duplicate Model or Prefab

Hi! I model some buildings import from Blender and try to duplicate to many of them. Should I just duplicate from the model or create a prefab of it first? Any differents?

What are you going to do with the duplicates?

just level design, place the building everywhere

I would create prefab from it first.
And than use prefab. I would never use raw model.
That way you can modify it later or even exchange it completely.