fjord vs inlet

fjord and inlet both are nouns.

Word	Noun	Adjective	Verb	Adverb
fjord	Yes	No	No	No
inlet	Yes	No	No	No

As nouns, inlet is a hypernym of fjord; that is, inlet is a word with a broader meaning than fjord:

fjord: a long narrow inlet of the sea between steep cliffs; common in Norway
inlet: an arm off of a larger body of water (often between rocky headlands)

Other hypernyms of fjord include recess.

fjord (noun)	inlet (noun)
a long narrow inlet of the sea between steep cliffs; common in Norway	an opening through which fluid is admitted to a tube or container
	an arm off of a larger body of water (often between rocky headlands)