I had to do a report about this awhile ago. If I remember correctly 4G is capable of 100Mbps and 3G is capable of 10Mbps. Currently 3G is at around 2-4Mbps. What they consider 4G might be faster but it's more like a 3.5G
I like how companies say they have 4G when they really don't even have 3G. We haven't reached the potential of 3G yet and the towers out there right now can't even support 4G speeds, yet they up the cost and give us almost nothing.