Does each “buzz” give a different effect? How does the brain know which part to let the serotonin into to get a specific high? Like is there the same “buzz” between lets say alcohol, coke, heroin, gambling, cigarettes, weed or painkillers? How does your brain know how to let loose the “high” part? How does a alcoholic different from a alcoholic or gambling addict? Is there like a thin line that runs through all addictions? And this is why so many fall under the very vague umbrella of just addicts?? Can explain more if need be.
I don’t know any of the details you’re asking about.
But I can say addiction is defined by behaviour. It may not be exactly what you mean.
You might be thinking of chemical dependency. That’s how nicotine, opioids, and alcohol work. Those are specific to each drug.
Things like gambling and sex addiction are based on different chemical processes, and largely work the same, whatever the addictive behaviour may be.
But again my knowledge here is pretty limited.