Generics allow for type-safe collections by specifying type parameters. This ensures type safety during compilation and prevents runtime errors. Some benefits of generics include no casting or boxing, increased performance, and a strongly typed model. Common generics include generic classes, interfaces, methods, and constraints. Iterators provide a way to navigate through collection values using foreach and simplify iteration by returning values without storing the entire collection in memory. The main difference between IEnumerator and IEnumerable is that IEnumerable defines the GetEnumerator() method to retrieve an IEnumerator, while IEnumerator defines the methods like Current, Reset(), and MoveNext() to iterate over values.