Do We Really Speak the Same Language?

I was talking to my friend Eva the other day, and I realized that sometimes it feels like we speak completely different languages although we both speak Spanish. E is from Barcelona and I am from Argentina . The interactions with my friend made me think of the differences between the Spanish spoken in Argentina and in Spain, and how distressing it could be for Spanish students visiting Argentina, for example if they learned Castilian Spanish, or the other way around. Below are a few distinctions that come to mind.
Grammar: Tú or Vos?
If you are an English native speaker, and you are planning to travel to Argentina , and to make use of your almost perfect Spanish, you will need to learn how to use the second informal pronoun vos instead of tú. Vos is more or less the equivalent to thee in English. Conjugating vos is actually simpler than tú since there are no irregular verbs to deal with other than ser, which changes to sos instead of eres. For instance:
Volver: tú vuelves –> vos volvés
Dormir: tú duermes –> vos dormís
Ser: tú eres –> vos sos
In Accent: To lisp or not to lisp, that is the question
Unlike Spaniards, Argentineans do not lisp. Instead, they use the /s/ sound for the z, s, ce and ci combinations. For instance, in Spain casa, cazar, vencer, and decir are pronounced with a /th/ sound while in Argentina they use the /s/ sound.
Daily words: Words that you may need to know to get by in Argentina if you studied Castilian Spanish.
<!--[if !supportLists]-->· <!--[endif]-->Strawberry – It’s frutilla, not fresa.
<!--[if !supportLists]-->· <!--[endif]-->Peach – It’s durazno, not melocotón.
<!--[if !supportLists]-->· <!--[endif]-->Juice – It’s jugo. It’s definitely not zumo. And even that wouldn’t be with a lisp.
<!--[if !supportLists]-->· <!--[endif]-->Computer – It’s computadora. Much easier to use than an ordenador.
<!--[if !supportLists]-->· <!--[endif]-->Potato – It’s papa, and it is not your daddy, it’s a potato. Spaniards would say patata.
<!--[if !supportLists]-->· <!--[endif]-->Nightclub – It’s boliche. Discoteca sounds lame and old-fashioned.
<!--[if !supportLists]-->· <!--[endif]-->Sandwich – It’s sándwich. In Spain , it´s torta.
<!--[if !supportLists]-->· <!--[endif]-->Cake – It´s torta in Argentina and not pastel. If you ask for pastel, you will probably end up getting a fried empanada or a dish similar to meatloaf.
Isn’t this too confusing? I understand. I am so lucky I did not have to study Spanish as a second language.