brown oak vs flowering tree

brown oak and flowering tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
brown oak	Yes	No	No	No
flowering tree	Yes	No	No	No

As nouns, flowering tree is a hypernym of brown oak; that is, flowering tree is a word with a broader meaning than brown oak:

Other hypernyms of brown oak include angiospermous tree.

brown oak (noun)	flowering tree (noun)
large tree of Australasia	any tree having seeds and ovules contained in the ovary