Silver fir and White fir

Silver fir noun - Any of various true firs having leaves white or silvery white beneath.

White fir and silver fir are semantically related. In some cases you can replace phrase "White fir" with "Silver fir", this phrases are similar.

White fir noun - Medium to tall fir of central to western United States having a narrow erect crown and soft wood.

Silver fir and white fir are semantically related. You can use "Silver fir" instead a noun phrase "White fir".