nature study vs enquiry

nature study and enquiry both are nouns.

Word	Noun	Adjective	Verb	Adverb
nature study	Yes	No	No	No
enquiry	Yes	No	No	No

As nouns, enquiry is a hypernym of nature study; that is, enquiry is a word with a broader meaning than nature study:

nature study: the study of animals and plants in the natural world (usually at an elementary level)
enquiry: a search for knowledge

Other hypernyms of nature study include inquiry, research.

nature study (noun)	enquiry (noun)
the study of animals and plants in the natural world (usually at an elementary level)	a systematic investigation of a matter of public interest
	a search for knowledge
	an instance of questioning