Fine-pitch components are SMD components where the leads are spaced very close together. IPC calls the SMDs fine-pitch from a center-to-center (lead distance) of 0.65 mm and smaller.
There are also ultra-fine-pitch components, which have a center-to-center distance of 0.3 mm and smaller (usually QFPs (Quad Flat Pack), but there are also other types of SMD components).