It depends in which country you are -
In US, cilantro was always a leafy herb, and coriander a powder that is ground from the coriander seeds. Cilantro (is the Spanish word for coriander leaves. It is also sometimes called Chinese or Mexican parsley.
Though in other countries i.e. South Asia and Middle East Coriander refers to the whole plant i.e. seeds as well as leafy herb so in these countries there is no difference between Coriander & cilantro.