white cedar vs cedar tree

white cedar and cedar tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
white cedar	Yes	No	No	No
cedar tree	Yes	No	No	No

As nouns, cedar tree is a hypernym of white cedar; that is, cedar tree is a word with a broader meaning than white cedar:

white cedar: slow-growing medium-sized cedar of east coast of the United States; resembles American arborvitae
cedar tree: any of numerous trees of the family Cupressaceae that resemble cedars

Other hypernyms of white cedar include cedar.

white cedar (noun)	cedar tree (noun)
slow-growing medium-sized cedar of east coast of the United States; resembles American arborvitae	any cedar of the genus Cedrus
small evergreen of eastern North America having tiny scalelike leaves on flattened branchlets	any of numerous trees of the family Cupressaceae that resemble cedars