fissure vs hilus

fissure and hilus both are nouns.

Word	Noun	Adjective	Verb	Adverb
fissure	Yes	No	Yes	No
hilus	Yes	No	No	No

As nouns, hilus is a hyponym of fissure; that is, hilus is a word with a more specific, narrower meaning than fissure:

fissure: (anatomy) a long narrow slit or groove that divides an organ into lobes
hilus: (anatomy) a depression or fissure where vessels or nerves or ducts enter a bodily organ

Other hyponyms of fissure include sulcus, hilum.

fissure (noun)	hilus (noun)
(anatomy) a long narrow slit or groove that divides an organ into lobes	(anatomy) a depression or fissure where vessels or nerves or ducts enter a bodily organ
a long narrow cleft
a long narrow depression in a surface

fissure (verb)	hilus (verb)
break into fissures or fine cracks