I've used it sometimes when - for example - a friend says a colour is light blue, I say it's medium blue, so as we both see things differently and one person's perception of light/medium/dark, etc, is different from another's, we're still talking about the same thing in the end - give an take - so it's the same difference.
An oxymoron: when a person uses two words at the same time which have contradictory meanings i.e Cruel kindness.
Hope this helps; I'm not very good at explaining the meaning of words.