body process vs activity

body process and activity both are nouns.

Word	Noun	Adjective	Verb	Adverb
body process	Yes	No	No	No
activity	Yes	No	No	No

As nouns, body process and activity are synonyms defined as:

body process and activity: an organic process that takes place in the body

Other synonyms of body process include bodily function, bodily process.

body process (noun)	activity (noun)
an organic process that takes place in the body	any specific behavior
	the trait of being active; moving or acting rapidly and energetically
	an organic process that takes place in the body
	a process existing in or produced by nature (rather than by the intent of human beings)
	the state of being active
	(chemistry) the capacity of a substance to take part in a chemical reaction