The former has a monoclinic crystal structure whereas the latter has a hexagonal crystal structure. They vary in their colours with lepidolite having a greyish pink colour and amethyst being found in nature of purple to lilac coloured. The hardness varies too. For the record, amethyst is harder than lepidolite. Lepidolite has got rich lithium content and thus has anxiety-relieving benefits whereas amethyst is a type of quartz which finds application in reducing addiction in people.