The difference between Near and Nigh

When used as prepositions, near means close to, in close proximity to, whereas nigh means near.

When used as adverbs, near means having a small intervening distance with regard to something, whereas nigh means almost, nearly.

When used as verbs, near means to come closer to, whereas nigh means to draw nigh (to).

When used as adjectives, near means physically close, whereas nigh means near, close by.

Near is also noun with the meaning: the left side of a horse or of a team of horses pulling a carriage etc.

check bellow for the other definitions of Near and Nigh

Near as an adjective:

Physically close.
Near as an adjective:

Closely connected or related.
Near as an adjective:

Close to one's interests, affection, etc.; intimate; dear.

Examples:

"a near friend"
Near as an adjective:

Close to anything followed or imitated; not free, loose, or rambling.

Examples:

"a version near to the original"
Near as an adjective:

So as barely to avoid or pass injury or loss; close; narrow.

Examples:

"a near escape"
Near as an adjective (of an event):

Approaching.

Examples:

"The end is near."
Near as an adjective:

Approximate, almost.

Examples:

"The two words are near synonyms."
Near as an adjective (dated):

Next to the driver, when he is on foot; on the left of an animal or a team.

Examples:

"the near ox; the near leg"
Near as an adjective (obsolete):

Immediate; direct; close; short.
Near as an adjective (obsolete, slang):

Stingy; parsimonious.

Near as an adverb:

Having a small intervening distance with regard to something.

Examples:

"I'm near-sighted."
Near as an adverb (colloquial):

nearly

Near as a preposition:

Close to, in close proximity to.

Examples:

"There are habitable planets orbiting many of the stars near our Sun."
Near as a preposition:

Close to in time.

Examples:

"The voyage was near completion."

Near as a verb (ambitransitive):

To come closer to; to approach.

Examples:

"The ship nears the land."

Near as a noun:

The left side of a horse or of a team of horses pulling a carriage etc.

Nigh as an adjective (archaic, poetic):

near, close by

Examples:

"The end is nigh!"
Nigh as an adjective:

Not remote in degree, kindred, circumstances, etc.; closely allied; intimate.

Nigh as a verb (ambitransitive):

To draw nigh (to); to approach; to come near.

Nigh as a preposition:

near; close to

Examples:

"When the Moon is horned ... is it not ever nigh the Sun?"