field of study vs domain

field of study and domain both are nouns.

Word	Noun	Adjective	Verb	Adverb
field of study	Yes	No	No	No
domain	Yes	No	No	No

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

Other hypernyms of field of study include knowledge base, knowledge domain.

field of study (noun)	domain (noun)
a branch of knowledge	the content of a particular field of knowledge
	people in general; especially a distinctive group of people with some shared interest
	(mathematics) the set of values of the independent variable for which a function is defined
	territory over which rule or control is exercised
	a particular environment or walk of life