In large part these various labels are interchangeable. Each implies a rejection of methodological exclusiveness, and each rests on a somewhat misleading contrast with a positivist orthodoxy which never actually existed, since neither functionalism nor abstracted empiricism ever held hegemonic sway over the theory and practice of sociology during the previous period. Marxism, idealism, and symbolic interactionism (to take only the most obvious examples) offered ever-present philosophical and methodological alternatives.
"methodological pluralism." A Dictionary of Sociology. . Encyclopedia.com. (August 20, 2018). http://www.encyclopedia.com/social-sciences/dictionaries-thesauruses-pictures-and-press-releases/methodological-pluralism
"methodological pluralism." A Dictionary of Sociology. . Retrieved August 20, 2018 from Encyclopedia.com: http://www.encyclopedia.com/social-sciences/dictionaries-thesauruses-pictures-and-press-releases/methodological-pluralism