invariable

As nouns the difference between taxonomy and invariable

is that taxonomy is the science or the technique used to make a classification while invariable is something that does not vary; a constant.

As an adjective invariable is

not variable; unalterable; uniform; always having the same value.

Unchangeable is a antonym of invariable.

As adjectives the difference between invariable and unchangeable

is that invariable is not variable; unalterable; uniform; always having the same value while unchangeable is not changeable; incapable of being changed or of changing; immutable.

As nouns the difference between invariable and unchangeable

is that invariable is something that does not vary; a constant while unchangeable is something that cannot be changed.