Slate is natural stone;
A tile is manufactured.
A ‘slate tile’ is a piece of slate cut and prepared for use as a tile.

Tiles, for covering surfaces such as roofs, walls and floors, are made from a variety of hard-wearing materials. These include natural slate, fired clay and concrete.

Slate is a fine-grained metamorphic rock that can be split easily into thin layers. Mainly grey in colour, a wide variety of textures, colour varieties and irregular patterns can be found in slate.