"Social democracy" doesn't mean anything though. The most precise definition I can guess at is something like, ordinary capitalism with a more generous welfare programme than America.

Socialism has a fairly clear definition though. It's only tangentially related to social safety nets and other related things. Socialist countries often have huge wealth disparities and being poor in them is much worse than being poor in America.

Dude, they do tend to be a bit overly simplistic about it, but don't need to insult them for it. Just point out and move on. (P.S: I am not even american)