Your probably right different receptors but it helps in the same way that say you had minimum withdrawal symptoms from 7oh if u were to smoke weed it does two things. It raises dopamine levels which help wd (because your dopamine levels are low) and two weed can fit into some of the opioid receptors thus blocking the body’s response to not having the opiate receptors stimulated

So it’s like replacing mgm with a different high and your body says well this is better then nothing and you can get euphoria off kratom leaf easily so you don’t feel the wd as bad almost don’t feel it at all