Final answer:
The class attribute is for assigning one or more elements the same class name, which is helpful for applying shared styles or behaviors, whereas the id attribute gives a unique identifier to a single element, facilitating precise styling or targeting in scripts and internal linking.
Step-by-step explanation:
The difference between an HTML class attribute and an HTML id attribute lies in their usage and uniqueness. The class attribute is used to specify a class name for an HTML element. Multiple elements can share the same class name, allowing you to style or manipulate a group of elements with the same class simultaneously. On the other hand, the id attribute provides a unique identifier to a single HTML element, which can be used for styling, but more importantly, it can be used as a way to target the element uniquely through JavaScript or for internal linking (creating anchor links within a page).