The difference between Gigantic and Monster

When used as adjectives, gigantic means very large, whereas monster means very large.

Monster is also noun with the meaning: a terrifying and dangerous creature.

Monster is also verb with the meaning: to make into a monster.

check bellow for the other definitions of Gigantic and Monster

Monster as a noun:

A terrifying and dangerous creature.
Monster as a noun:

A bizarre or whimsical creature.

Examples:

"The children decided Grovyle was a cuddly monster."
Monster as a noun:

An extremely cruel or antisocial person, especially a criminal.

Examples:

"Get away from those children, you meatheaded monster!"
Monster as a noun (medicine, archaic):

A horribly deformed person.
Monster as a noun (figuratively):

A badly behaved child, a brat.

Examples:

"Sit still, you little monster!"
Monster as a noun (informal):

Something unusually large.

Examples:

"Have you seen those powerlifters on TV? They're monsters''."
Monster as a noun (informal):

A prodigy; someone very talented in a specific domain.

Examples:

"That dude playing guitar is a monster."
Monster as a noun (gaming):

A non-player character that player(s) fight against in role-playing game.

Monster as an adjective (informal):

Very large; worthy of a monster.

Examples:

" He has a monster appetite."

"rfquotek Alexander Pope"
Monster as an adjective (informal):

Great; very good; excellent.

Monster as a verb:

To make into a monster; to categorise as a monster; to demonise.
Monster as a verb:

To behave as a monster to; to terrorise.
Monster as a verb (chiefly, Australia):

To harass.