na-adjective
Describes something physically small or finely divided, or a detailed, meticulous approach. Also used for a stingy, petty attitude toward money or details.
この紙を細かく切ってください。
Please cut this paper into small pieces.
彼は細かいところまでよく気がつく。
He notices even the smallest details.
あの人はお金に細かい。
That person is stingy with money.
細かい is the more common i-adjective form with the same meanings; 細か is a na-adjective variant used in similar contexts but less frequent.
小さい means 'small' in size or scale, while 細か emphasizes fineness, detail, or granularity.
Derived from the classical adjective 細し (こまし), meaning 'fine' or 'detailed'. The na-adjective form 細か developed from the stem 細か-.