What are the key differences between the diamond structure and graphite, and how do these variances impact their properties and applications?

The key differences between diamond and graphite lie in their atomic structure and bonding. Diamond has a three-dimensional network of carbon atoms bonded together in a tetrahedral arrangement, making it extremely hard and durable. Graphite, on the other hand, consists of layers of carbon atoms arranged in a hexagonal lattice, allowing for easy sliding between layers. This difference in structure results in diamond being hard and transparent, while graphite is soft and opaque. These variances impact their properties and applications, with diamond being used in cutting tools and jewelry due to its hardness, and graphite being used as a lubricant and in pencils due to its slippery nature.