valley oak vs roble

valley oak and roble both are nouns.

Word	Noun	Adjective	Verb	Adverb
valley oak	Yes	No	No	No
roble	Yes	No	No	No

As nouns, valley oak and roble are synonyms defined as:

valley oak and roble: tall graceful deciduous California oak having leathery leaves and slender pointed acorns

Other synonyms of valley oak include California white oak, Quercus lobata, valley white oak.

valley oak (noun)	roble (noun)
tall graceful deciduous California oak having leathery leaves and slender pointed acorns	tall graceful deciduous California oak having leathery leaves and slender pointed acorns
	large tree of Trinidad and Guyana having odd-pinnate leaves and violet-scented axillary racemes of yellow flowers and long smooth pods; grown as a specimen in parks and large gardens