I was in the supermarket this morning and noticed that they had two varieties of the regular garlic.
The first was labelled 白蒜 (Mand: bái suàn; Cant: baak6 syun3 ), 'white garlic'.
The second was 香蒜 (Mand: xiāng suàn; Cant: hoeng1 syun3), where 香 means 'fragrant; sweet-smelling; aromatic; scented; savoury; appetizing; perfume or spice' among others.
I had just bought a batch of the single headed variety in the farmer's market, so passed on these. I may do a taste test in the future to see what the difference is, if any.