A:Answer The NS-55D420NA18 is a little bit lighter, has lower powered speakers, is a little bit more energy efficient, and has a slightly larger bezel. It also has an analog audio output, which the NS-55D410NA17 does not have. You can see a side-by-side comparison, here: http://www.bestbuy.com/site/compare?skus=5692400,4806800&productString=*&url=%2Fsite%2Fsearchpage.jsp%3Fst%3Dinsignia%2B55%2522%26_dyncharset%3DUTF-8%26id%3Dpcat17071%26type%3Dpage%26sc%3DGlobal%26cp%3D1%26nrp%3D%26sp%3D%26qp%3D%26list%3Dn%26af%3Dtrue%26iht%3Dy%26usc%3DAll%2BCategories%26ks%3D960%26keys%3Dkeys.