bur oak vs burr oak

bur oak and burr oak both are nouns.

Word	Noun	Adjective	Verb	Adverb
bur oak	Yes	No	No	No
burr oak	Yes	No	No	No

As nouns, bur oak and burr oak are synonyms defined as:

bur oak and burr oak: medium to large deciduous oak of central and eastern North America with ovoid acorns deeply immersed in large fringed cups; yields tough close-grained wood

Other synonyms of bur oak include mossy-cup oak, mossycup oak, Quercus macrocarpa.

bur oak (noun)	burr oak (noun)
medium to large deciduous oak of central and eastern North America with ovoid acorns deeply immersed in large fringed cups; yields tough close-grained wood	medium to large deciduous oak of central and eastern North America with ovoid acorns deeply immersed in large fringed cups; yields tough close-grained wood