How is antithesis different from paradox?
They are different rhetorical devices
Although both may have words or phases that seem contradictory or opposite, Antithesis and Paradox are two different rhetorical devices. Antithesis relies on contrast, generally emphasizing the scale, magnitude or importance of two events, where as paradox is a confusing statement that usually conveys hidden truth after some thought.
"Antithesis is a rhetorical device in which two opposite ideas are put together in a sentence to achieve a contrasting effect"
Ex: "Setting foot on the moon may be a small step for a man but a giant step for mankind." Here there is a contrast between small and giant.
"is a statement that appears to be self-contradictory or silly but may include a latent truth."
My favorite example is from George Orwell's Animal Farm : "All animals are equal, but some are more equal than others." Here, the statement seems silly because equality should be exactly equal, not more equal. However, this statement reveals the latent truth that beneath the thin veneer of equality is blatant political hierarchy.