Difference between Fiend and Monster

Fiend

Part of speech: noun

Definition: A demon A very evil person An addict

Example sentence: I was once a shameless, full-time dope fiend.

Monster

Part of speech: noun

Definition: A terrifying and dangerous, wild or fictional creature.A bizarre or whimsical creature.An extremely cruel or antisocial person, especially a criminal.A horribly deformed personA badly behaved child, terrible brat.A prodigyA bodybuilder of exceptionally large weight and proportions, typically weighing more than 135 kilos (300 lbs).

Part of speech: adjective

Definition: Very large; worthy of a monster.

Part of speech: verb

Definition: To harass

Example sentence: You have to go to what the essence of what Pennywise is about - the dark power of adulthood. It's not coincidence all the grown-ups in town are evil. This is not a story about a monster. It's a story about the end of childhood.