What's the difference between standard unit blocks and a 100-piece colorful set?

Standard unit blocks are unpainted hardwood in mathematically proportioned shapes (the half-unit, unit, double-unit system used in preschool classrooms). The colorful 100-piece sets are smaller, lighter, painted, and aimed at home play. Reviewers describe unit blocks as the more open-ended, longer-lasting option; the colorful sets as more visually engaging for younger toddlers.