The difference for me is, I will fight for Ken's right to disagree with me (and I assume most of us) over such an extreme interpretation of "Free Speech," whereas the "I can own slaves and fuck you up if I want to because "LIBERTY"" dudes can fuck right off.
Certainly, but my point is that there's always a conflict between my liberty to do something, and your freedom peacefully to go about your lawful business unmolested.
Slavery is obviously an extreme example, but the rights of enslavers not to have their liberty infringed, despite the harm it did to their victims, was a huge part of American political and legal thought, and I think that bias in favour of the individual's liberty as the expense of others is still very much there in US legal and politico-legal thinking.
Almost every time some right-wing US group takes up an issue under the Bill of Rights or subsequent constitutional amendments, before too long some right-wing British group tries something similar in our courts, quoting an equivalent provision under the ECHR.
Despite the fact the cases usually make their way to the US Supreme Court, the equivalent cases over here hardly ever get anywhere, and when they do, our Supreme Court generally finds against the right-wing provocateur, even though, on the face of it, the Bill of Rights and the ECHR protect pretty much the same things in most cases.
That's because, I think, there's a whole strand of protection for people's rights to go about their normal business in peace and unmolested by others that's very important in our legal tradition but doesn't seem to exist in the US -- for example, our courts recognise the right of women to attend abortion clinics, and staff to work there, free from harassment and intimidation as outweighing the right of protestors to freedom of assembly and speech, to the extent that local councils can create large no-go zones around clinics if necessary (subject always to judicial oversight) where such protests are prohibited.
That, as I understand it, just wouldn't be possible in the US, even if a local council had the political will to do it.