faithfulness vs fidelity

faithfulness and fidelity both are nouns.

Word	Noun	Adjective	Verb	Adverb
faithfulness	Yes	No	No	No
fidelity	Yes	No	No	No

As nouns, faithfulness and fidelity are synonyms defined as:

faithfulness (noun)	fidelity (noun)
the quality of being faithful	the quality of being faithful
	accuracy with which an electronic system reproduces the sound or image of its input signal