Kimmeridgean vs Oxfordian - What's the difference?

kimmeridgean | oxfordian | coordinate terms |

Kimmeridgean is a coordinate term of oxfordian.

As a noun oxfordian is

a native or resident of oxford.

As a proper noun oxfordian is

(geology) the age from 1635±10 ma to 1573±10 ma or the stage of rocks (chiefly coral-derived limestones) deposited during it.

As an adjective oxfordian is

of or pertaining to oxford or its residents.