There is a strict, legal hierarchy of olive oil grades, and the marketing words on the front of a bottle map onto it precisely — once you know the code. From best to worst:
The top grade. Mechanically extracted (pressed or centrifuged) with no heat or chemicals, free acidity ≤ 0.8%, and zero sensory defects on a tasting panel. This is the only grade that delivers the full flavour and the full load of antioxidants and polyphenols. Buy this, and ideally buy it fresh.
Also mechanically extracted and unrefined, but with slightly higher acidity (≤ 2%) and minor sensory flaws. Perfectly edible, a notch below extra virgin, and rarely seen on supermarket shelves in many countries.
When virgin oil is defective (acidity above 2%, or off-flavours), it is refined with heat, solvents or both to strip out the defects — and with them, the flavour, colour and most health compounds. A little virgin oil is blended back in for taste and colour, and the result is sold as plain 'olive oil', 'pure' or 'classic'. Fine for high-heat frying; not where the flavour or the health story lives.
A marketing term, not a legal grade. It is refined olive oil with a very mild flavour and pale colour. 'Light' refers only to taste and colour — the calories are identical to every other olive oil.
The bottom rung. Extracted with solvents from the leftover paste (pomace) after pressing, then refined. Legal and cheap, used in catering and some processed foods, but a world away from extra virgin. Avoid for anything where flavour or health matters.