The difference between Unchangeable and Variable

When used as nouns, unchangeable means something that cannot be changed, whereas variable means something that is variable.

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

check bellow for the other definitions of Unchangeable and Variable

Unchangeable as an adjective:

Not changeable; incapable of being changed or of changing; immutable.

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.