health spa vs fat farm

health spa and fat farm both are nouns.

Word	Noun	Adjective	Verb	Adverb
health spa	Yes	No	No	No
fat farm	Yes	No	No	No

As nouns, fat farm is a hyponym of health spa; that is, fat farm is a word with a more specific, narrower meaning than health spa:

health spa: a place of business with equipment and facilities for exercising and improving physical fitness
fat farm: a health spa that specializes in helping people lose weight

health spa (noun)	fat farm (noun)
a place of business with equipment and facilities for exercising and improving physical fitness	a health spa that specializes in helping people lose weight