Rigamajig® is much larger, and has many more parts to share. It's intended for 2-20 kids to play together in a supervised environment. Teachers across the US have been developing lesson plans that use Rigamajig® to learn simple machines, mathematics, STEAM topics, and much much more. Best yet, the students design ways to use it in the classroom and all around the school.
Rigamajig® Jr. is great for 1-4 kids to play with. It requires less open space, and stores away in it's own gym-bag sized duffel.