Speed difference between Zong SUPER 3G and normal 3G

What is the speed difference between Zong SUPER 3G and normal 3G available in Pakistan?

Zong SUPER 3G will offer speeds of up to 42 Mbps while normal 3G offers speeds of up to 21 Mbps. So Zong SUPER 3G is twice as fast as normal 3G available in Pakistan.