We use several different structures for comparing.

Similarity

To say that people, things or actions are similar in a way, we can use as and like. Adverbs such as too, also and as well can also be used.

She looks just like her mother.
He fought like a lion.
He fought as a lion does.
The papers were late and the post was too.

Structures such as so do I and neither do I can also be used.

She doesn’t like meat, and neither do I.
She likes music, and so do I.

To say that people or things are identical in a way, we can use the same as.

Her eyes are just the same color as mine.

To talk about differences we use the negative forms of these structures.

She doesn’t look like her mother.

Her eyes are not the same color as yours.

Equality

To say that people or things are equal in a way, we use the structure as…as or as much/many…as.

She earns as much money as he does.

In negative comparisons we can use not as…as or not so…as.

She doesn’t earn so much money as he does.

To say that people or things are unequal in a way we use comparative adjectives and adverbs with than.

She is taller than you.
She is more intelligent than her husband.

We can also use less than or least to talk about inequality.

She earns less than I do. OR I earn more than she does.
She is less ugly than you. OR You are uglier than her.