A superlative adjective is used to compare three or more things or people, indicating the highest degree of a quality among them. In English, superlative adjectives are often formed by adding "-est" to shorter adjectives 

A comparative adjective is used to compare two things or people, showing a difference in degree between them. In English, comparative adjectives are usually formed by adding "-er" to shorter adjectives (like "bigger" from "big") or using "more" before longer adjectives (like "more beautiful" from "beautiful"). 

The cheetah is the fastest land animal, reaching speeds of up to 70 miles per hour."

EXPLANATION: "fastest" is a superlative adjective. Superlatives are used to compare three or more things and indicate that one has the highest degree of a certain quality. In the case of the cheetah, it is described as the "fastest land animal," which means it can run faster than any other land animal. 

The elephant is larger than the lion.

EXPLANATION: "larger" is a comparative adjective. Comparative adjectives are used to compare two things and indicate that one has more or less of a certain quality than the other.