If you don't know the difference between 3G and 4G, then i will tell you. 3G is is technology that is wireless that gives customers high speed transmission, advanced multimedia access, and global roaming facilities. Now this a service that has been around for awhile. The 3G network also gives customers able to serf the internet, upload videos or pictures, and the important thing, to make phone calls.
4G is like a step foward to service offered. It would allow customers to have ultra-broad brand internet and gaming service. It also has multimedia facility.
3G and 4G have a difference in some cases. For example, their data rate. 3G has a 2Mbps for walking users or people who are stationed in one place and 4G has a 1Gits. For when you are in a moving vehicle the 3G is set to 384 Kbits and 4G is set to 100 Mbit. Also as you read in the definitions in 3G and 4G, you can see a difference there as well.
In today's networks, Verizon, At&t, and Sprint are the ones that offer the 4G but T-mobile says they offer it but don't have it.