Coarse threads have a larger pitch, or the distance between threads, than fine threads. This means that there are fewer threads per unit of measurement, such as per inch, on a coarse thread than on a fine thread. As a result, coarse threads are less precise and have lower tensile strength than fine threads. However, they are generally easier to create and better suited for applications where strength and precision are not as critical, such as wood or plastic.
On the other hand, fine threads have a smaller pitch, are more precise, and have a higher tensile strength than coarse threads. They are often used in applications where a high level of precision and strength is required, such as in metal parts.