dowser vs diviner

dowser and diviner both are nouns.

Word	Noun	Adjective	Verb	Adverb
dowser	Yes	No	No	No
diviner	Yes	No	No	No

As nouns, diviner is a hypernym of dowser; that is, diviner is a word with a broader meaning than dowser:

dowser: someone who uses a divining rod to find underground water
diviner: someone who claims to discover hidden knowledge with the aid of supernatural powers

dowser (noun)	diviner (noun)
forked stick that is said to dip down to indicate underground water or oil	someone who claims to discover hidden knowledge with the aid of supernatural powers
someone who uses a divining rod to find underground water