Tiles are composed of Elements (floors, doors, walls, props, etc; whatever you decide to place).
In your Assembly (environment) you’ll likely have multiple Tiles.
In the Builder Tool we compare Tiles to each other; those that have the same Elements, in the same number, are NOT considered unique. Everything else IS unique.
For example, let’s say you make a Tile using Floor A, and Wall B, and you compare it with another Tile using Floor A and Wall B; those are identical Tiles and are therefore NOT unique. If the second Tile had Floor A and 2x Wall B, then they would be unique Tiles.