Cumin (jintan putih) is a more popular herb which is used widely in Chinese, Indian, Malay and Middle eastern dishes. In fact, cumin is the world's second most popular spice after black pepper!
Cumin can be bitter or sweet; with earthy/musky/pungent/spicy notes of lemon, nuts and smoke. Whereas fennel (jintan manis) as a sweet flavour with notes of anise and/or licorice, and a crunchy texture.