The difference between Addition and Reduction

When used as nouns, addition means the act of adding anything, whereas reduction means the act, process, or result of reducing.

check bellow for the other definitions of Addition and Reduction

Addition as a noun (uncountable):

The act of adding anything.

Examples:

"The addition of five more items to the agenda will make the meeting unbearably long."
Addition as a noun:

Anything that is added.
Addition as a noun (uncountable):

The arithmetic operation of adding.
Addition as a noun (music):

A dot at the right side of a note as an indication that its sound is to be lengthened one half.
Addition as a noun (chiefly, legal):

A title annexed to a person's name to identify him or her more precisely, as in "John Doe, Esq.", "Robert Dale, Mason", "Thomas Way, of New York".
Addition as a noun (heraldry):

Something added to a coat of arms, as a mark of honour; opposed to .

Reduction as a noun:

The act, process, or result of reducing.
Reduction as a noun:

The amount or rate by which something is reduced, e.g. in price.

Examples:

"A 5% reduction in robberies"
Reduction as a noun (chemistry):

A reaction in which electrons are gained and valence is reduced; often by the removal of oxygen or the addition of hydrogen.
Reduction as a noun (cooking):

The process of rapidly boiling a sauce to concentrate it.
Reduction as a noun (mathematics):

The rewriting of an expression into a simpler form.
Reduction as a noun (computability theory):

a transformation of one problem into another problem, such as mapping reduction or polynomial reduction.
Reduction as a noun (music):

An arrangement for a far smaller number of parties, e.g. a keyboard solo based on a full opera.
Reduction as a noun (philosophy, phenomenology):

A philosophical procedure intended to reveal the objects of consciousness as pure phenomena. (See phenomenological reduction.)
Reduction as a noun (medicine):

A medical procedure to restore a fracture or dislocation to the correct alignment.