Why do people from spain or whatever people get mad when i call them Mexicans Hispanics?

Ok i live in Kentucky and we see people that speak Spanish as Mexicans. So this guy came from Spain i guess and he was speaking Spanish to his wife in line and i said what part of Mexico you guys from and he said sorry sir we are Spaniards and we are considered Latinos/White.. I said waaaaaait a minute look at me! I'm the white/Caucasian here your not white and then he said they were Latinos,, So my question is Latinos are Mexicans so wouldn't they be considered Mexican?? I'm the white person here so i have no clue what he is trying to say but he aint no white! Then i said what different does it make you speak Spanish so your Mexicans/Hispanics.. We in the south think people that speak Spanish is a Mexican.. What do you guys think?? I didnt even know people from spain even spoke spanish, so they dont speak any english?? So wouldnt spain be part mexicans since they speak spanish? Southern White Pride!!!