Answer:
1) Presence and importance: Spain is a country with more history and maybe with a better economic situation, which allows them to have a stronger presence in the education in general, having better-equiped schools and easier access to schools, especially in smaller towns.
2) Vocabulary: In both countries the language used is Spanish, but there are different approaches to it, where some words change, and the accent changes.
3) School system: Where in Mexico there is a more common system (preescolar, primaria and secundaria) in Spain you have the same start, but instead of secundaria there is the "ESO" (Educación secundaria obligatoria) that last from 12 to 16, and after that comes the "educación secundaria posobligatoria" that you only can access after you have your ESO title, where the courses are of "half a degree" and you can choose what you want depending on the career you want to follow.