The difference between Backup and Relief

When used as nouns, backup means a reserve or substitute, whereas relief means the removal of stress or discomfort.

When used as adjectives, backup means standby, reserve or extra, whereas relief means characterized by surface inequalities.

check bellow for the other definitions of Backup and Relief

Backup as a noun:

A reserve or substitute.

Examples:

"If the goalkeeper is injured, we have a backup."
Backup as a noun (computing):

A copy of a file or record, stored separately from the original, that can be used to recover the original if it is destroyed or damaged.

Examples:

"After the power failure, we had to restore the database from backup."
Backup as a noun:

An accumulation of material caused by a (partial) obstruction or (complete) blockage of the flow or movement of the material, or an accumulation of material that causes an overflow due to the flow being greater than the maximum possible flow.

Examples:

"The accident caused a mile-long backup on the highway."

"The blockage caused a backup in the plumbing."
Backup as a noun (law enforcement):

reinforcements

Examples:

"He's got a gun! You'd better send for backup."

Backup as an adjective:

Standby, reserve or extra.

Examples:

"I am only a backup player."
Backup as an adjective (computing):

That is intended as a backup.

Examples:

"Make a backup copy of that file."

Relief as a noun:

The removal of stress or discomfort.

Examples:

"I sighed with relief when I found out that my daughter hadn't got lost, but was waiting for me at home."
Relief as a noun:

The feeling associated with the removal of stress or discomfort.
Relief as a noun:

The person who takes over a shift for another.

Examples:

"Officer Schmidt can finally go home because his relief has arrived."
Relief as a noun:

Aid or assistance offered in time of need.
Relief as a noun (legal):

Court-ordered compensation, aid, or protection, a redress.
Relief as a noun:

A lowering of a tax through special provisions; short for tax relief.

Relief as a noun:

A type of sculpture or other artwork in which shapes or figures protrude from a flat background.
Relief as a noun:

The apparent difference in elevation in the surface of a painting or drawing made noticeable by a variation in light or color.
Relief as a noun:

The difference of elevations on a surface.

Examples:

"the relief on that part of the Earth's surface"

Relief as an adjective (of a surface):

Characterized by surface inequalities.
Relief as an adjective:

Of or used in letterpress.