dyspepsia vs upset stomach

dyspepsia and upset stomach both are nouns.

Word	Noun	Adjective	Verb	Adverb
dyspepsia	Yes	No	No	No
upset stomach	Yes	No	No	No

As nouns, dyspepsia and upset stomach are synonyms defined as:

dyspepsia and upset stomach: a disorder of digestive function characterized by discomfort or heartburn or nausea

Other synonyms of dyspepsia include indigestion, stomach upset.

dyspepsia (noun)	upset stomach (noun)
a disorder of digestive function characterized by discomfort or heartburn or nausea	a disorder of digestive function characterized by discomfort or heartburn or nausea