Castilian Spanish – so named for its roots in the region of Castile – emerged from Spain’s many regional languages and dialects to become the primary language of the nation. Castilian Spanish was later brought to the New World through the colonization efforts of the Spanish, where the language enjoyed widespread adoption throughout the Americas. Over time, Latin American Spanish has evolved in its own right to contain various features that distinguish it from European Spanish.
The use of the term “castellano” as opposed to “español” when referring to the Spanish language may be interpreted in a number of ways. Since there are several official languages in Spain including Catalan, Basque, and Galician, the word “castellano” is often used to differentiate the Spanish language from these regional languages. Castellano may also be used to refer to regional dialects of the Spanish language spoken in Castile, for example, Andalusian. Many times – particularly outside of Spain – castellano and español are utilized interchangeably and simply refer to the Spanish language as a whole.
The terms Castilian Spanish or castellano are often used to draw a distinction between the Spanish spoken in Spain (Peninsular Spanish) and Latin American Spanish; however, this usage is somewhat misleading since Spanish speakers in Latin America also speak what are essentially dialects of Castilian Spanish as opposed to a distinct language, as is often implied.
Many Spanish speakers in Latin America customarily refer to their language as castellano as opposed to español. For example, Southern Cone countries such as Argentina and Uruguay have a tendency to refer to Spanish as castellano, while other parts of South America alternate between the use of the terms español and castellano. In the U.S., Mexico, Central America and the Caribbean, Spanish is almost exclusively referred to as español.
While there is no generic form of Latin American Spanish, many countries share several features of pronunciation, vocabulary and grammar that set apart Latin American Spanish from Castilian Spanish.
Read more about Latin American Spanish and Castilian Spanish