안 (+지 않다) vs. 못 (+지 못하다)

What is the difference between 안 (+지 않다) and 못 (+지 못하다)?

안 (+지 않다):

1. Combines with both verbs and adjectives.

For example:

- 학교에 안 가요. (I don't go to school.)

- 치마가 안 예뻐요. (The skirt is not pretty.)

2. Express not doing something regardless of ability or external conditions.

For example:

- 저는 운전을 안 해요. (I don't drive.)

- 오늘은 쇼핑을 하지 않아요. (I won't go shopping today. I simply don't feel like going shopping.)

못 (+지 못하다):

1. Combines with verbs, but not normally with adjectives.

For example:

- 학교에 못 가요. (I can't go to school.)

- 치마가 못 예뻐요. (×)

2. Used when one is unable, or it is impossible, to do something.

For example:

- 저는 운전을 못해요. (I can't drive.)

- 오늘은 쇼핑을 하지 못해요. (I can't go shopping today. I want to go shopping, but can't due to some external circumstance, such as lack of money or time.)

Source:

[1] Ahn Jean-myung, Lee Kyung-ah, Han Hoo-young, Korean Grammar in Use Beginning to Early Intermediate, page 66.