What is the difference between superlative relative adjectives and superlative absolute adjectives?

Superlative relative adjectives tell us that someone or something has a certain quality to the maximum within a group of people or objects. For example, say that you are looking at all the people in your class and you notice that your friend David is the tallest out of all of them. In Italian you would say: "David è il più alto della mia classe" (David is the tallest in my class).Superlative absolute adjectives tell us that the person or object we are looking at has a certain quality to the maximum, but we are not comparing him/her/it to anything it anyone else. You want to state that your friend David is really tall, so you simply say: "David è altissimo"