Hello,I found that on WikiAnswers but it seems to be a too simple explanation to me:
"Hispanic refers to Spain and its culture and people, and is especially applied to Americans whose first language is Spanish.
Latin refers to the language of ancient Rome, but is also used to describe a person from a country whose language developed from Latin: for example, Latin American."
Have a look at this as well:
http://www.elboricua.com/latino_hispanic.html
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