In Downton Abbey,is there a difference between the American version and the United Kingdom version?

[Madeline]

I have a few questions about Downton Abbey!! I have heard that the American version is shorter than the UK version and that we miss some scenes (is this true and if so what do we miss?)...So I live in America and I have never watched Downton Abbey on the TV. I watched the first season on Netflix. So for the first season on Netflix I was wondering if it was the original version or the American version.

I bought season 2 at the store on DVD in America and I was wondering if there was any difference in that too, like is it shorter and missing scenes?

I know that season 3 airs in America on January 6, 2013 and I was just wondering is that the same for the United Kingdom, or has it already aired there bc, and if it has aired in the United Kingdom how long ago? Like does it air in the United kingdom before it airs in America?

So when January 6 comes and when I start watching Downton Abbey season 3 here in America will it be shorter than it is in the United Kingdom? and if it is shorter where can I see the entire episode?
by the way Thanks!!!!!!!