Complex sentence: In English, the term "Spanish" relates more to the language than to the nation; the noun used today for a person from Spain is "Spaniard" and the term "Castilian" is much less widespread than the use of "Spanish".
Split into simpler sentences: In English, the term Spanish relates more to the language than to the nation; the noun used today for people from Spain is "Spaniard". Also, the use of the term "Castilian" is much less widespread than the use of "Spanish".