사회민주주의
Because social democracy originated as a revolutionary socialist or communist movement, one distinction made to separate the modern versions of democratic socialism and social democracy is that the former can include revolutionary means while the latter asserts that the only acceptable constitutional form of government is representative democracy under the rule of law. Many social democrats "refer to themselves as socialists or democratic socialists" and some "use or have used these terms interchangeably." Others argue that "there are clear differences between the three terms, and preferred to describe their own political beliefs by using the term 'social democracy' only." Social democracy is the evolutionary form of democratic socialism that aims to gradually and peacefully achieve socialism through established political processes such as the parliament. In political science, "democratic socialism" and "social democracy" are largely seen as synonyms and as overlapping or otherwise not being mutually exclusive while they are distinguished in journalistic use, in some cases sharply. Although social democrats continue to call and describe themselves as "democratic socialists" or simply "socialists", the meanings of "democratic socialism" and "social democracy" have effectively reversed. "Democratic socialism" originally represented socialism achieved by democratic means and usually resulted in reformism whereas "social democracy" included both reformist and revolutionary wings. With the association of social democracy as policy regime and the development of the Third Way, "social democracy" became almost exclusively associated with reformism while "democratic socialism" came to include communist and revolutionary tendencies.