downhearted vs grim

downhearted and grim both are adjectives.

Word	Noun	Adjective	Verb	Adverb
downhearted	No	Yes	No	No
grim	No	Yes	No	No

As adjectives, downhearted and grim are synonyms defined as:

Other synonyms of downhearted include blue, depressed, dispirited, down, down in the mouth, downcast, gloomy, low-spirited, low.

downhearted (adjective)	grim (adjective)
filled with melancholy and despondency	shockingly repellent; inspiring horror
	filled with melancholy and despondency
	causing dejection
	not to be placated or appeased or moved by entreaty
	harshly ironic or sinister
	harshly uninviting or formidable in manner or appearance