system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: The difference between Serotonin, Dopamine, and Endorphins

I understand they’re all pleasure/happiness/reward neurotransmitters (I think?) but what’s the difference?
gpt
Really short version:

Endorphins block pain receptors.  They're basically natural opioids and function in a really similar manner.  They produce a similar feeling of euphoria to other opioids.

Dopamine controls how much you are rewarded for a positive action.  It doesn't directly produce a feeling of pleasure but rather increases the desire to perform the action again.

Serotonin regulates mood.  More generally means that you're happier while less tends to mean you're not happy.  It doesn't directly cause pleasure either.

Of course, all of these have numerous other functions but you seemed to be most concerned with brain states.