We use comparatives and superlatives to speak about the degree to which things are different. Comparatives usually point out the differences between two elementnts, and superlatives highlight the element which has the most of a certain quality in a group. With superlatives, we often talk about our personal experience with the Present Perfect. 

Check these examples:

• The black horse is bigger than the brown and white one. 

• That pony is the cuttest animal I've ever seen.

Comparatives and superlatives have very similar rules, and these depend on the number of syllables of the adjective. There are some cases in which more than one form is acceptable. Let's see these rules.

We can use as + adj + as... to say that two things are the same. For example:

"He's as tall as his coworker."

We can use this expression in the negative to say that two things are different. The thing that is less of that description goes at the beginning, and the one that is more goes at the end. For example:

"My father isn't as old as yours." - My father's age (45) < your father's (68).