Flagstone

Flagstone is a flat stone, usually used for paving slabs or walkways, patios, fences and roofing. It may be used for memorials, headstones, facades and other constructions. The name derives from Middle English flagge meaning turf, perhaps from Old Norse flaga meaning slab or chip.

Building Stone

Building stone is rock that is used in the construction of buildings, retaining walls, bridges, and other structures and includes building components such as walls, foundations, sills, chimneys, and steps.
The most desirable building stones have a combination of strength, durability, beauty, and ease of quarrying, cutting, and carving.