Both XL and XXL blocks are configured exactly the same. The only differences are size and dimension. Here's the full-size breakdown:
XL is 60 percent from XXL block size.
XXL are 7.87x3.94x3.94in (20x10x10cm). XL are 5.11x2.56x2.56in (13x6.5x6.5cm).
XL and XXL bloks sizes are not compatible. However, some of our customers like to purchase multiple sizes to make it possible for children to create multiple structures.