From what I remember of my LSD taking days, LSD nausea is more akin to the feeling of sickness you get when you've gone too long without eating; a butterflies in the stomach, combined with a lead ball rolling around your empty stomach. 5-MeO AMT felt more like a vertigo sort of nausea, where nothing would stay still in front of your eyes, when contrasted with everything else in your field of vision.
Only difficulty is; if you've never had LSD, you could be fooled into thinking that the nausea from the two is similar