fine line

Noun

idiomatic

(idiomatic) A difference, albeit vague and difficult to discern.

Japanese Meaning

微妙な違い / 明確に識別しにくい、僅かな差異

There is a fine line between confidence and arrogance, and it's easy to cross when you're not self-aware.

自信と傲慢の間の違いは紙一重で、自己認識が欠けていると簡単に越えてしまう。

Sense（1）

(idiomatic) A difference, albeit vague and difficult to discern.

There's a fine line between fishing and just standing on the shore like an idiot.

fine lines

（ plural ）