common elder vs black elder

common elder and black elder both are nouns.

Word	Noun	Adjective	Verb	Adverb
common elder	Yes	No	No	No
black elder	Yes	No	No	No

As nouns, common elder and black elder are synonyms defined as:

common elder and black elder: a common shrub with black fruit or a small tree of Europe and Asia; fruit used for wines and jellies

Other synonyms of common elder include bourtree, elderberry, European elder, Sambucus nigra.

common elder (noun)	black elder (noun)
a common shrub with black fruit or a small tree of Europe and Asia; fruit used for wines and jellies	a common shrub with black fruit or a small tree of Europe and Asia; fruit used for wines and jellies