Sorry, I meant that Nirvana had more in common with the Melvins than the other grunge guys they got lumped in with.
80s grunge would define in as starting with the slowed down hardcore from the early-mid 80s (My War era Black Flag, Flipper’s first album, Blight, YDI) and continuing on through the later period hardcore records that no one apart from people in Seattle seemed to give a shit about (Die Kreuzen’s October File, I Against I by Bad Brains, Redd Kross’ Neurotica, Animosity by Corrosion Of Conformity) stuff like that. Then the Seattle/Aberdeen bands (U-Men, Melvins) and culminating with the early records by Tad, Mudhoney and Nirvana, which is pretty much where it ends (give or take a couple of decent records by some other bands). Not the whole story at all - really similar stuff was happening in Australia in particular - but think that’s the basics.