Lemmy has an abnormally tech literate and FOSS "aware" (there's got to be a better term but I'm blanking) user base. The community is small enough that recognizing people isn't unheard of so we tend to be more polite overall - with a smaller community there's less of a sense of anonymity and more social accountability. Oh, we tend to be rather left leaning but, to be honest, "The universe has a well known liberal bias".