The difference between Backup and Standby

When used as nouns, backup means a reserve or substitute, whereas standby means a state of readiness without immediate involvement.

Backup is also adjective with the meaning: standby, reserve or extra.

Standby is also verb with the meaning: to wait briefly, as for additional communication by radio or telephone.

check bellow for the other definitions of Backup and Standby

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."

Standby as a noun:

A state of readiness without immediate involvement; remaining in preparation for (a sudden or unforeseen event or situation).

Examples:

"The troops were on standby in case of an attack."
Standby as a noun (electronics):

sleep mode
Standby as a noun (travel):

Waiting at the airport in the hope of getting a seat on a flight that is already booked out.
Standby as a noun:

Something that is standard, well-tested, or frequently used.

Examples:

"That recipe is an old standby, and she keeps the ingredients around in case of unexpected guests."

Standby as a verb (proscribed, _, neologism, operations):

To wait briefly, as for additional communication by radio or telephone;

Examples:

"Standby while I check that for you."