A manual foot spa requires the user to manually fill and empty the basin with water, while an automatic foot spa has built-in water jets and a drainage system. Manual models tend to be more affordable and portable, but they require more effort and can't provide the same level of massage and stimulation as automatic models. Automatic models can be more convenient and offer a wider range of features, but they also tend to be larger and more expensive. Consider your needs and budget when choosing between manual and automatic foot spas.