Natural stone veneer installation includes selecting the proper materials with which to install the stones. Mortar and grout are two similar products with different purposes. They are both made of cement and an aggregate. Mortar comes in many strengths and formulas, which have various applications. Grout is sold in countless colors to help customize the look of your project. However, mortar is used to fasten materials together while grout is used to fill in gaps, typically for aesthetics. In the stone veneer industry, the terms mortar and grout are used interchangeably, since mortar is used both to fill gaps and make the stone stick to the surface.