I think this is actually a quite good question, lol.
I believe nowadays motonari is supposed to be more of a drugged style, where the model is not necessarily passed out but more like out of his mind, while in dead drunk obscenity the model is supposed to be completely drunk, which can include passed out or even asleep in some cases. But I'm not sure an average model can pull out that difference in a meaningful way, tho.
But the thing is, Motonari was not originally that. When it was first created and for the first... five? scenes or so it was always announced as and had the scenes description starting with フェチズムに特化した新メーカー『MOTONARI』("Motonari, a new brand specialized in Fetishism").
But o be honest, they seemed to be a bit lost with where to go with the "fetishism" concept and kept reusing what worked for the first scene, which was long socks and foot work. And there was clearly no drugged concept.
Until Masaya came.
And Masaya's Motonari with the drugged thing and his acting became so good and so popular that the whole series was pretty much co-opted lol.
I think nowadays Motonari's distinguishing characteristics would be de aesthetics, with the suit attire and dark illumination, that make it looks sorta fancy.