peace of mind vs heartsease

peace of mind and heartsease both are nouns.

Word	Noun	Adjective	Verb	Adverb
peace of mind	Yes	No	No	No
heartsease	Yes	No	No	No

As nouns, peace of mind and heartsease are synonyms defined as:

Other synonyms of peace of mind include ataraxis, peace, peacefulness, repose, serenity.

peace of mind (noun)	heartsease (noun)
the absence of mental stress or anxiety	the absence of mental stress or anxiety
	common Old World viola with creamy often violet-tinged flowers
	violet of Pacific coast of North America having white petals tinged with yellow and deep violet
	a common and long cultivated European herb from which most common garden pansies are derived