The difference between Nether and Subterranean

When used as adjectives, nether means lower, whereas subterranean means below ground, under the earth, underground.

Nether is also noun with the meaning: oppression.

Nether is also adverb with the meaning: down.

Nether is also verb with the meaning: to bring or thrust down.

check bellow for the other definitions of Nether and Subterranean

Nether as an adjective:

Lower; under.

Examples:

"The disappointed child’s nether lip quivered."
Nether as an adjective:

Lying beneath, or conceived as lying beneath, the Earth's surface.

Examples:

"The nether regions."

Nether as a verb (transitive, UK, _, dialectal, Northern England, Scotland):

To bring or thrust down; bring or make low; lower; abase; humble.
Nether as a verb (transitive, UK, _, dialectal, Northern England, Scotland):

To constrict; straiten; confine; restrict; suppress; lay low; keep under; press in upon; vex; harass; oppress.
Nether as a verb (transitive, UK, _, dialectal, Scotland):

To pinch or stunt with cold or hunger; check in growth; shrivel; straiten.
Nether as a verb (transitive, UK, _, dialectal, Scotland):

To shrink or huddle, as with cold; be shivery; tremble.
Nether as a verb (transitive, UK, _, dialectal, Scotland):

To depreciate; disparage; undervalue.

Nether as a noun (UK, _, dialectal, Scotland):

Oppression; stress; a withering or stunting influence.
Nether as a noun (mining):

A trouble; a fault or dislocation in a seam of coal.

Subterranean as an adjective:

below ground, under the earth, underground