grim vs downhearted

grim and downhearted both are adjectives.

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

As adjectives, grim and downhearted are synonyms defined as:

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

grim (adjective)	downhearted (adjective)
shockingly repellent; inspiring horror	filled with melancholy and despondency
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