@josephgomes619 personally, I think it's hentai when the characters in that series just shag
most of the time, if it's too bizarre and of course if there's genitals being shown.
If those 2/3 conditions didn't met, I think it's mostly smut.
And that's my opinion.
Also, I think I read what OP was talking about.
It involve drugs (bizarre part), the characters mostly shag, and there's genitals to be seen.
That title now have been classified as hentai.