How does a list data structure differ from an array in terms of their usage and characteristics?

In C#, arrays and List<T> have key differences:

• Array — a fixed-size data structure that stores elements of the same type. The size of the array is set at creation and cannot be changed. Arrays are efficient in memory and access speed because elements are stored contiguously.

• List<T> — a dynamic list from the System.Collections.Generic namespace. It can automatically expand when new elements are added. List<T> provides convenient methods for adding, removing, searching, and sorting elements.

Example:

int[] array = new int[3] {1, 2, 3};
// array[3] = 4; // Error, index out of range

List<int> list = new List<int>() {1, 2, 3};
list.Add(4); // List size increases automatically

Thus, if you need a fixed size and maximum performance — use an array. If you need flexibility and convenience in working with collections — use List<T>.