Final answer:
Iodine has a molecular crystal structure with diatomic molecules, while graphite has a hexagonal layered structure.
Step-by-step explanation:
The crystal structure of iodine is characterized as a molecular crystal, with each iodine molecule consisting of two iodine atoms bonded together. This structure involves weak Van der Waals forces holding the molecules in a crystal lattice. On the other hand, the crystal structure of graphite is a layered structure with a hexagonal arrangement of carbon atoms within each layer. The layers are held together by weak Van der Waals forces, allowing them to slide over one another, which makes graphite a good lubricant.