Bien:
* Adverb: Means "well" or "good" and modifies a verb, adjective, or another adverb.
* Example: "Elle chante bien" (She sings well).
* Adjective: Means "good" or "well" but is used in a more abstract way.
* Example: "C'est bien de voir tes amis" (It's good to see your friends).
* Pronoun: Can be used as a substitute for a noun or noun phrase, meaning "something good" or "what is good."
* Example: "Qu'est-ce qui est bien à manger ?" (What is good to eat?)
Bon:
* Adjective: Means "good" and modifies a noun.
* Example: "C'est un bon livre" (It's a good book).
* Noun: Can be used to mean "good" or "good things".
* Example: "Le bon et le mauvais" (The good and the bad).
Key Differences:
* Grammatical Function: "Bien" is primarily an adverb, while "bon" is an adjective.
* Meaning: "Bien" emphasizes the quality of an action or state, while "bon" describes the quality of a noun.
* Usage: "Bien" is more versatile and can be used in more contexts, while "bon" is more specific to describing nouns.
Examples to clarify:
* Bien: "Il est bien parti." (He left well).
* Bon: "C'est un bon gâteau." (It's a good cake).
Remember, the choice between "bien" and "bon" depends on the specific context and what you want to emphasize.