Ok that's though one for English native. Exemple : Ce repas sent bon : this food smell good ! Tu as déjà fini! C'est bien : you already done. That's quite good! Bien and bon => good. Most of the time "bon" is used like a adjectif or adverbe Bien is used like a adverbe. I think one tip I can give you it's most of the time "bien" it's used to give a compliment. And "bon" it's used generally like a adjectif. j'ai un bon contact avec lui : I have a good feeling with him However you need to practice to see all cases.

Hello, "Bon" is about good about feeling like food or touch or smell and thing and person, and "bien" is good about non physical things

https://frenchtogether.com/bien-bon/