teutonic

As a noun taxonomy

is the science or the technique used to make a classification.

As an adjective teutonic is

relating to the ancient germanic people, the teutons.

As adjectives the difference between celtic and teutonic

is that celtic is of the Celts; Of the style of the Celts while Teutonic is relating to the ancient Germanic people, the Teutons.

As a proper noun Celtic

is a branch of the Indo-European languages that was spread widely over western and central Europe in the pre-Christian era.