hygienics vs hygiene

hygienics and hygiene both are nouns.

Word	Noun	Adjective	Verb	Adverb
hygienics	Yes	No	No	No
hygiene	Yes	No	No	No

As nouns, hygienics and hygiene are synonyms defined as:

hygienics and hygiene: the science concerned with the prevention of illness and maintenance of health

hygienics (noun)	hygiene (noun)
the science concerned with the prevention of illness and maintenance of health	the science concerned with the prevention of illness and maintenance of health
	a condition promoting sanitary practices