Great timing! - We're restructuring a whole international successfully site with different languages and countries.
It's a global business, we sell products to different countries with different prices / specifications. Also, we offer the site multilingual.

Sometimes the product for Argentina and Portugal is the same product, and google detect it as duplicated content, something we need to work out.

We are now passing language as a variable, now reading im considering using subdomains. TLD isn't an option, unfortunately.

I delivery products for different coutnries, example: Argentina, Uruguay, United States, Portugal, etc. and also, we offer the site in 2 languages (spanish and english).

My question is: should I use (for example)
ar.domain.com - for country specific products
uy.domain.com - for country specific products
us.domain.com - for country specific products
pt.domain.com  - for country specific products
and show language according for domain - unfortunatelly with this option, user may want to surf on us.domain.com while in spanish language.

or

us.domain.com - for english language
es.domain.com - for spanish language

and leave country as a subdirectory ?

in this case, what happen from people that search for products in Argentina ? or Uruguay? the es subdomain will filter only the Spain country?

I will really appreciate any suggestion comments on my situation and I hope it helps others too. I planned doing the new structure of site next week but I will delay a little in pro of this post. Thanks for sharing.