The difference between Nether and Subsurface

When used as nouns, nether means oppression, whereas subsurface means something that is below the layer that is on the surface.

When used as adjectives, nether means lower, whereas subsurface means below the surface.

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 Subsurface

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.

Subsurface as a noun:

Something that is below the layer that is on the surface.

Examples:

"Before we could lay the flooring we had to lay a subsurface under it to keep it flat and support it."
Subsurface as a noun (countable, mathematics):

A surface which is a submanifold of another surface.

Subsurface as an adjective:

below the surface

Examples:

"variations in subsurface conditions"