Quercus cerris vs oak

Quercus cerris and oak both are nouns.

Word	Noun	Adjective	Verb	Adverb
Quercus cerris	Yes	No	No	No
oak	Yes	No	No	No

As nouns, oak is a hypernym of Quercus cerris; that is, oak is a word with a broader meaning than Quercus cerris:

Quercus cerris: large deciduous tree of central and southern Europe and Asia Minor having lanceolate leaves with spiked lobes
oak: a deciduous tree of the genus Quercus; has acorns and lobed leaves

Other hypernyms of Quercus cerris include oak tree.

Quercus cerris (noun)	oak (noun)
large deciduous tree of central and southern Europe and Asia Minor having lanceolate leaves with spiked lobes	a deciduous tree of the genus Quercus; has acorns and lobed leaves
	the hard durable wood of any oak; used especially for furniture and flooring