How much does Spanish-latin amercan and Spanish-spain differ?

I notice when chosing Spanish as the language I wanted to learn on Rosetta stone that I had a choice between paying for the Spanish/Latin Amercan disc or the Spanish/Spain disc…they were both the same price but completely different expensive products.
How much do they differ? very little I assume…?…?
Please advise.
For example, how much trouble would a Mexican have communicating freely and confidently in Spain with the locals if that Mexican were to travel to Spain in Europe on vacation? Would he be able to communicate as well as an american that traveled to England? Or is this a bad example?
Please tell me some differences between latin American spanish and Spain spanish…with examples.
Thank you very much for your time;
Perry in FL
I am currently trying to learn Espanol using the latin american version of the Rosetta stone cd’s
How much do these languages differe from each other? very little I assume….maybe mostly only the slang? Please advise. Do they mostly differ in words, syntax, or both…or very very little?
I would have thought very little until I saw that I had to choose between spending three hundred dollars to learn Spanish/latin Amercan or spend the $399 for the Spain version….WTF??
Thanks again
Would a person from one easily be able to commincate with a person from the other?
A Spaniard visiting Mexico and vice-versa…..what are some examples of any differences?

I have no problem understanding a person from Spain at all. The only real difference in accent is that the c and z sound like a lisp and the s is softer. Of course different words are preferred in each country but speakers of the Spanish speaking world know those words already. Slang of course is different in every country but I doubt Rosetta delves too deep into that anyway. Words are spelled the same throughout the Spanish speaking world since we have a language academy that regulates grammar and spelling (Royal Spanish Academy) unlike English. My guess is that Latin American Spanish on here really means Mexican Spanish since like someone else said, Argentina uses vos. Newsflash: A lot of central American countries like Guatemala also use vos so it is not just limited to Spain. Go for the cheapest one since once you have a good knowledge of the language you will be able to understand different forms like vos, vosotros, etc, easily without previous study. In conclusion, Spanish does NOT have different spelling and grammar when you move to another country like English does, it is the same everywhere except for slang and preferred words. A person will always have trouble understanding certain regional dialects (I can’t understand some Mexicans and I am one) and slang but like I said, once you know the language all you have to do is ask about a certain word. I do this all the time when the Guatemalans I know use a word unique to their country.