American Arborvitae vs. Emerald Green: What's the Difference?

The American Arborvitae (Thuja occidentalis) and the Emerald Green

 both species of evergreen tree in the cypress family.

The main difference between the two is their size

 American Arborvitae is a large tree that can grow up to 60 feet tall

Emerald Green Arborvitae is a smaller cultivar that typically grows to around 15-20 feet

Emerald Green Arborvitae has a more pyramidal shape with a denser, 

Both trees are popular as ornamental plants and are used as privacy hedges.