[quote=The New Yorker]
It's not less potent, but instead less addictive. Moon sugar is actually a hallucinogenic drug, like acid or ahyusca, whereas skooma simply causes psychoactive effects like more dopamine or serotonin.
[/quote]

Moon sugar's effects actually aren't nearly as potent. For Khajiit, it is used as a spice and it takes quite a lot to incapacitate one of them. It is quicker for non-Khajiit, but not nearly as quick as skooma.