This is not how the US immigration system works. America issues two types of visas: immigrant and non-immigrant visas. The "green card" in question is, in fact,

This is not how the US immigration system works. America issues two types of visas: immigrant and non-immigrant visas. The "green card" in question is, in fact, the end product an immigrant spousal visa (IR1 and CR1). There is also a non-immigrant spousal visa called K-3. Here in the EU it works differently, as my wife is a family member of an EU citizen (me) she automatically has the right of freedom of movement within the EU. The UK Border Agency has issued her a residence document to confirm her status but it's not a visa or an endorsement in away way; it's just a confirmation of her existing rights.