sincerity vs earnestness

sincerity and earnestness both are nouns.

Word	Noun	Adjective	Verb	Adverb
sincerity	Yes	No	No	No
earnestness	Yes	No	No	No

As nouns, sincerity and earnestness are synonyms defined as:

Other synonyms of sincerity include serious-mindedness, seriousness.

As nouns, sincerity and earnestness are synonyms defined as:

Other synonyms of sincerity include seriousness.

sincerity (noun)	earnestness (noun)
the quality of being open and truthful; not deceitful or hypocritical	the trait of being serious
the trait of being serious	an earnest and sincere feeling
a quality of naturalness and simplicity
an earnest and sincere feeling