a fine line between something

a fine line between something

COMMON If there is a fine line between two different activities or situations, there is a point at which they are very similar, often when one activity or situation is acceptable, and the other is not. There is a fine line between being nicely looked after and being fussed over too much. A new exhibition explores the fine line between genius and insanity. Note: You can also talk about a thin line between two things or a narrow line between two things. There is a thin line between being a good player and being one of the best. There's a narrow line between being interested and being nosy. Compare with walk a fine line between something.
See also: fine, line, something