Spanish music is music that comes from Spain. Latin music is a term used to describe music that encompasses the whole Latin American world, including Spain.
Spanish music varies in style and tone as it pertains to the region of Spain where it originates. This means that music from Castile sounds uniquely different from music of the Basque region of Spain.
Latin music is not pure Spanish. Latin music has a blend of other genres. Puerto Rican, Dominican and Cuban music are examples of Latin music that have been influenced by African rhythms, due to slavery and New World explorations of Christopher Columbus and Ponce de Leon.
South American Latin music has been influenced by major exploration as well, but leans heavily on Native American influence and other world explorers stemming from Portugal, Germany, Holland and Italy.
Even though salsa dominates Puerto Rican music, it originated in Cuba. Cuban music can be differentiated by a piccolo sound throughout the music piece. Reggaeton is Panamanian as well as Puerto Rican.
Not all Latin music speaks the same Spanish language. It depends on the country that the music comes from and what other countries in history influenced that country. Some Latin music has a German omm-bop-bop, while others make you want to dance around a campfire. There's music to make you calypso sway, other music to make you dance disco and yet another kind to break dance, hip-hop or put your hands in the air!