In general, their brick quality isn't on par with Lego. The clutching of Lego bricks is finely weighed and consistent. The colouring is brighter. They don't have nasty toxic smells and paints. The set catalogues are more diverse with many more themes. Set designs are original and matching the age group. There is also historical significance and nostalgia for certain sets and themes, and they can be re-released as new sets with modern building techniques and new parts.