People have compared it to drinking strong salt water, or even bleach, especially since it has a strong after taste and irritates your throat. Here's some threads about it I found in the searches:
Post #11 describes it in this thread:
https://sanctioned-suicide.net/thre...ut-taking-the-lethal-dose.22216/#post-1395017
Post #2 in the thread describes it as washing powder:
https://sanctioned-suicide.net/threads/how-does-sn-taste-like.46722/
If the search function works for you here's the searches that popped up:
https://sanctioned-suicide.net/search/693182/?q=Taste+of+SN&o=relevance
And to answer your question how close regular salt and SN taste I would say SN is much saltier and has a chemically bitter taste from what I've read of the various accounts on here. I'm sure there are survivors of this method that could describe it better than me. But remember to do your own research and use the search function.