Oxfordian is a coordinate term of tithonian.
As proper nouns the difference between tithonian and oxfordian
is that tithonian
is an age or stage, from 152.1±0.9 MY to ~145.0 Ma while Oxfordian
is the age from 163.5±1.0 Ma to 157.3±1.0 Ma or the stage of rocks (chiefly coral-derived limestones) deposited during it.
As a noun Oxfordian is
a native or resident of Oxford.
As an adjective Oxfordian is
of or pertaining to Oxford or its residents.