The difference between Invariable and Variable

When used as nouns, invariable means something that does not vary, whereas variable means something that is variable.

When used as adjectives, invariable means not variable, whereas variable means able to vary.

check bellow for the other definitions of Invariable and Variable

Invariable as an adjective:

Not variable; unalterable; uniform; always having the same value.
Invariable as an adjective (math):

Constant.
Invariable as an adjective (by extension, grammar, of a word, or a grammatical class):

That cannot undergo inflection, conjugation or declension.

Examples:

"The French adjective <u>marron</u> (brown) is invariable: it does not take the usual <u>s</u> in the plural."

Variable as an adjective:

Able to vary.

Examples:

"variable winds or seasons; a variable quantity"
Variable as an adjective:

Likely to vary.
Variable as an adjective:

Marked by diversity or difference.
Variable as an adjective (mathematics):

Having no fixed quantitative value.
Variable as an adjective (biology):

Tending to deviate from a normal or recognized type.

Variable as a noun:

Something that is variable.
Variable as a noun:

Something whose value may be dictated or discovered.

Examples:

"There are several variables to consider here."
Variable as a noun (mathematics):

A quantity that may assume any one of a set of values.
Variable as a noun (mathematics):

A symbol representing a variable.
Variable as a noun (programming):

A named memory location in which a program can store intermediate results and from which it can read them.
Variable as a noun (astronomy):

A variable star.
Variable as a noun (nautical):

A shifting wind, or one that varies in force.
Variable as a noun (nautical, in the plural):

Those parts of the sea where a steady wind is not expected, especially the parts between the trade-wind belts.