expression
that night; that evening
Refers to a specific night or evening already mentioned or understood from context.
その晩はよく眠れなかった。
I couldn't sleep well that night.
expression
over the course of the evening; during that evening
Emphasizes the duration or events happening throughout that evening.
その晩のうちに雨がやんだ。
The rain stopped over the course of the evening.