People from both countries can speak a version of Spanish that is mutually intelligible. But if you go into a high school (or even listen to adults that are being very casual) then it'd sound wildly different.
I speak Chilean Spanish. Distinctive characteristics include no use of vos; the "tú" conjugation is often "-ai" (cómo estai?) or "-i" (qué teni allí?); saying weón every sentence; using "po" for emphasis (sí po!); specific words like "fome" (boring), "la raja" (awesome), "bacán" (cool); phrases like "estoy cagado de hambre", "estoy chato", "pasarlo chancho", "cachai?"...
It's also very related to class, at least in Chile. Even I struggle to understand people in tougher neighborhoods of Santiago.
I speak Chilean Spanish. Distinctive characteristics include no use of vos; the "tú" conjugation is often "-ai" (cómo estai?) or "-i" (qué teni allí?); saying weón every sentence; using "po" for emphasis (sí po!); specific words like "fome" (boring), "la raja" (awesome), "bacán" (cool); phrases like "estoy cagado de hambre", "estoy chato", "pasarlo chancho", "cachai?"...
It's also very related to class, at least in Chile. Even I struggle to understand people in tougher neighborhoods of Santiago.