Fennel and cumin are not the same. Both seeds belong to the Apiaceae family, but are harvested from different plants. There is a distinct flavor difference between the two. Cumin has an aromatic earthy taste, which can be bitter. Fennel seeds taste similar to licorice. Both seeds can be used for cooking, adding strong flavor to a dish. However, they aren’t interchangeable. Cumin can be a substitute for fennel, but the better option is star anise or anise seeds. To substitute cumin, the best options are caraway seeds or ground coriander. Fennel is also used to refer to the fennel bulb. This is a vegetable that’s popular for use in salads, but can also be cooked. Similar to fennel seeds, it has a strong licorice taste. You can substitute fennel bulb with the seeds, but this will greatly alter the texture of the dish.