Both Chilean and Argentinians speak spanish or a derivation of it called castellano, which is a little different from the spanish from Spain. Add to it the different accent. When you come here you will know what I am talking about. Many people know some English so you can communicate here, no problem.

Local Spanish
Chile Spanish is usually speaked rapidly, some tend not to modulate so well, seeming to swallow some words, but please feel free just to ask to speak slower.

In Argentina, spanish is spoken like singing, yes, singing. Influence from Italians make Argentinians to overmodulate and emphasize phrases and words.

Even though you can find people who speaks english it is not a bad idea for you to learn some spanish. We give you here some tips if you would like to do so. Go for it!

Pronouncing Spanish
The are some strong differences between English and Spanish, please note this:

Getting Around...
Find here some typical phrases used when going around:

Food

Numbers

In case of Emergency