Amount and number

Use amount with uncountable nouns like rice, water, wheat etc. Use number with countable nouns.

He bought a large amount of rice. (Rice is uncountable.)

He bought a large number of apples. (Apples are countable.)

Anxious and eager

You are anxious when you feel nervousness. Eager means full of enthusiasm and impatience.

We are anxious about his health.
We are eager to see him healthy again.

Apt and liable

Apt means likely. Liable means having legal responsibility for something, especially costs and damages.

He is apt to get angry.
Rash driving will make you liable to a heavy fine.

Artisan and artist

Artisan is a skilled craftsperson. An artist is a creator of art.

Picasso was a great artist.
That carpenter is a good artisan.

Climate and weather

Climate refers to the typical weather in a particular region. Weather refers to the state of atmosphere at a particular time.

The weather was stormy. (The weather can change in a short period of time.)
I prefer a slightly warm climate. (The climate does not change in a short period of time.)

Couple and pair

The term couple refers to two people sharing lives or two people doing something together. Pair means two similar things used together.

There were a few couples on the dance floor.

I must buy a pair of shoes.

Despise and detest

To despise is to regard something with loathing and contempt. To detest is to hate or dislike something.

We shall not despise the poor.
I detest living in a hot climate.

Former and latter

Former means the first of two people or things mentioned. Latter means the second of two people or things mentioned.

I liked the latter half of the film. The former half seemed rather dull.

Habit and custom

The term habit refers to a behavior pattern that gets repeated regularly. The term custom refers to a social convention carried on by tradition.

It is his habit to get up at 6 am.
It is a custom among Hindus to cremate the dead.

In and into

In shows position inside something. Into shows movement.

There are many fish in the pond.
He fell into the river.
Many and much

Use many with countable nouns. Use much with uncountable nouns.

I have many friends.
I have read many books.
I don’t have much money.