the difference is simple, addiction is the compulsive/habitual action of something that does not have positive effects, more likely negative than neutral. For example, being "addicted" to gym is fine, because even if you enjoy the dopamine after, not the
actual exercise, it's still good for you overall, and you cannot really overdo it. Caffeine makes you more productive, and you cannot really spiral, hence why caffeine is legal, but opioid drugs are not.
But for tech, scrolling tiktok for 5 hours a day, definitely does not have positive outcomes. It's like gambling. It's dopamine hit for dopamine hit's sake, and the delivery system is actively harming you.