Historian: Our American Association for the Advancement of Science was founded in 1848. Membership in AAAS is open to everyone interested in science, unlike membership in NAS which is honorary election by existing members. Heading the AAAS "About" page is this: "The American Association for the Advancement of Science is an international non-profit organization dedicated to advancing science for the benefit of all people."
Physicist: AAAS does not do science unlike NAS where doing science is a big part of the mission. AAAS does publish science journals including the weekly Science which is one of the handful of top science publications. A big part of the AAAS mission is science advocacy including science policy advocacy and advocacy on issues where science and human rights overlap [link].
AAAS home page — much to explore here [link]
Science home page — much important info here [link]