white fir vs silver fir

white fir and silver fir both are nouns.

Word	Noun	Adjective	Verb	Adverb
white fir	Yes	No	No	No
silver fir	Yes	No	No	No

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

white fir: medium to tall fir of western North America having a conic crown and branches in tiers; leaves smell of orange when crushed
silver fir: any of various true firs having leaves white or silvery white beneath

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

white fir: medium to tall fir of central to western United States having a narrow erect crown and soft wood
silver fir: any of various true firs having leaves white or silvery white beneath

white fir (noun)	silver fir (noun)
medium to tall fir of western North America having a conic crown and branches in tiers; leaves smell of orange when crushed	any of various true firs having leaves white or silvery white beneath
medium to tall fir of central to western United States having a narrow erect crown and soft wood