Synonym:

* Definition: A synonym is a word that has the same or nearly the same meaning as another word.

* Example:

* Happy and Joyful are synonyms.

* Large and Big are synonyms.

Antonym:

* Definition: An antonym is a word that has the opposite meaning of another word.

* Example:

* Hot and Cold are antonyms.

* Happy and Sad are antonyms.

Key Differences:

* Meaning: Synonyms share a similar meaning, while antonyms have opposite meanings.

* Usage: Synonyms can often be used interchangeably in a sentence, while antonyms create a contrast.

Here's a helpful way to remember:

* Syn (like in "synonym") sounds like "same."

* Ant (like in "antonym") sounds like "opposite."