Ash tree and Fraxinus Americana

Ash tree noun - Any of various deciduous pinnate-leaved ornamental or timber trees of the genus Fraxinus.

Fraxinus Americana and ash tree are semantically related. In some cases you can replace phrase "Fraxinus Americana" with "Ash tree", this phrases are similar.

Fraxinus Americana noun - Spreading American ash with leaves pale green or silvery beneath and having hard brownish wood.

Ash tree and Fraxinus Americana are semantically related. You can use "Ash tree" instead a noun phrase "Fraxinus Americana".