Ground mustard and mustard seeds are both from the mustard plant, but they have different properties. Mustard seeds are the whole seeds of the plant, while ground mustard is made by grinding the seeds into a powder. Because it's ground, it's more potent and has a stronger flavor than whole seeds. Ground mustard is often used in cooking to add flavor to dishes, while whole mustard seeds are used in pickling and as a spice in stews and soups. Overall, the main difference between ground and seeds is their texture and intensity of flavor.