English question, please help?

English is ONLY a (badly spoken) language
made up of several others french Greek Latin
German and IS NOT a race nor a nationality

I always think of a correspondent as being in far-flung localities reporting on big events. A reporter just observes and writes the facts. A journalist has a broader perspective and more in depth writing.

All three are interchangeable and not mutually exclusive job titles and job roles.

No difference. All are excellent story tellers.