Can Someone Answer A Question About Spanish?

I'm learning Spanish & my in-laws are Hispanic. I've noticed the grammar & words used in teaching tools(like online) and the Spanish I hear are different. Is there a difference in Spanish that is taught from school books and the Spanish that's spoke in Mexico? ex. "Hija" is daughter, but I hear "Mija" and "Carne" is "Meat" from what I've learned from family...what is the difference? My fiance says Spanish from Spain sounds too formal here in the Southwest & in Mexico.