Sylvian fissure vs fissure of Sylvius

Sylvian fissure and fissure of Sylvius both are nouns.

Word	Noun	Adjective	Verb	Adverb
Sylvian fissure	Yes	No	No	No
fissure of Sylvius	Yes	No	No	No

As nouns, Sylvian fissure and fissure of Sylvius are synonyms defined as:

Sylvian fissure and fissure of Sylvius: the deepest and most prominent of the cortical fissures; separates the frontal lobes and temporal lobes in both hemispheres

Other synonyms of Sylvian fissure include lateral cerebral sulcus, sulcus lateralis cerebri.

Sylvian fissure (noun)	fissure of Sylvius (noun)
the deepest and most prominent of the cortical fissures; separates the frontal lobes and temporal lobes in both hemispheres	the deepest and most prominent of the cortical fissures; separates the frontal lobes and temporal lobes in both hemispheres