Citrus tree and Mandarin orange

Citrus tree noun - Any of numerous tropical usually thorny evergreen trees of the genus Citrus having leathery evergreen leaves and widely cultivated for their juicy edible fruits having leathery aromatic rinds.

Mandarin orange and citrus tree are semantically related. In some cases you can replace phrase "Mandarin orange" with "Citrus tree", this phrases are similar.

Mandarin orange noun - Shrub or small tree having flattened globose fruit with very sweet aromatic pulp and thin yellow-orange to flame-orange rind that is loose and easily removed; native to southeastern Asia.

Citrus tree and mandarin orange are semantically related. You can use "Citrus tree" instead a noun phrase "Mandarin orange".