Weird to call it "Spanish". Catalan is also "Spanish" (though you'll find a very small number of speakers in Southern France). Usually Catalan is opposed to Castilian.
Castilian Spanish, when used in English, is often used to denote the dialects spoken in Spain, as opposed to the dialects spoken in Latin America. This is not the topic at hand here, so there isn't much point in calling it Castilian (especially since many English speakers would not be familiar with that term) over Spanish.
adjective
relating to Spain, its people, or its language.
1. the people of Spain.
2. a Romance language spoken in Spain and in much of Central and South America.