Colorado fir and Silver fir

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

Silver fir and Colorado fir are semantically related. In some cases you can use "Silver fir" instead a noun phrase "Colorado fir".

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

Colorado fir and silver fir are semantically related. Sometimes you can replace phrase "Colorado fir" with "Silver fir", this phrases are similar.