Part of the reason is that Argentines speak in slang. A lot! And another reason is that they speak Castillian Spanish which I learned has it's own unique vocabulary and a heavy useage of the vosotros. In fact, I would often get asked by other Argentines if I spoke Castillian when I was young - not Spanish.
Luckily, about 80% of Spanish is similar in all Latin American countries. The basics, at least, tend to be the same. So, I can understand and speak with my other Latin American brothers and sisters, however there is enough difference for us all to get confused at times.
I remember when I visited Argentina as a 17 year old. And my grandmother told me we were going to ride a collectivo. A what I thought. A collective? Come to find out a collectivo is a bus. Argentines out there probably think I'm a complete idiot for admitting this, but I had never heard that term before.
Same with a choripan that my cousin asked me if I wanted at a soccer game. Again, no idea what he was refering too. A choripan is a delicious Italian sausage sandwich, sort of like a hot dog, but much, much better.
The great thing I found . . . is a dictionary for Argetine Spanish, called Wally's Dictionary of Argentine Colloquialism and Culture. Now that I'm writing books with Argenitine characters, I'm very excited that someone was wonderful enough to put this out on the web. I had a great time reading through some of these and remembering my father using so many of these.
"Que quilombo hicieron esos chicos."
What a mess those kids made.
I remember that one from my dad : )
(photo credit: Flickr: Kristjan Gudmundsson)