What are differences between an "opposite" and "antonym" to a word?

Question

What are the differences between an "opposite" and "antonym"?

Answer 1

They're pretty much the same thing. But opposite means 'against', so North is the opposite of South. Antonym means the opposite meaning, so 'happy' and 'sad' are antonyms.

Answer 2

There is no difference; "opposite" and "antonym" are synonyms!