From Longman Dictionary of Contemporary Englisha fine line between something and somethinga fine line between something and somethingDIFFERENTif you say that there is a fine line between two different things, you mean that they are so similar that one can easily become the other There’s a fine line between bravery and recklessness. → fine
Examples from the Corpus
a fine line between something and something• It's a fine line between guilt and shame.• There's a fine line between clever and stupid and Warrant are nowhere near it. 