Extra means the oil contains no more than 0.8% of free oleic acid.
Virgin means the oil comes from a mechanical process, not a chemical one.
The purest grade extra virgin olive oil is the first cold pressed. It's neither filtered nor distilled. Refined olive oil however is filtered and also tasteless.
From the same page:
"The refining process removes colour, odour and flavour from the olive oil, and leaves behind a very pure form of olive oil that is tasteless, colourless and odourless and extremely low in free fatty acids"
I don't mean 'pure' in a good sense, just that it is a simple mixture.
Virgin means the oil comes from a mechanical process, not a chemical one.
The purest grade extra virgin olive oil is the first cold pressed. It's neither filtered nor distilled. Refined olive oil however is filtered and also tasteless.
https://en.wikipedia.org/wiki/Olive_oil#Commercial_grades