The difference between 3G and 4G technolgy is speed. 3G is third generation, which is what most wireless technology use and 4G is fourth generation; which just makes it more powerful. If you’ll recall, 1G and 2G came before, with each one becoming faster, more secure and reliable. So, getting a 4G wireless router means it should perform at the highest level. We are talking must faster data transfer speeds.
The standard for 4G must be around 100 Megabits per second and up to 1 Gigabit per second. However, it might be confusing, but 4G is not true 4G – yet. True 4G is not expected until late 2013. On 3G/4G devices, the speeds are somewhere between 3G and 4G. Probably when you start to see aggressive marketing for 5G, you’ll have true 4G performance.
Also, you might see the term LTE 4G – LTE stands for Long Term Evolution. It is simply a version of 4G. Right now, the International Telecommunications Union regulates the standard for 4G wireless technology. To make it more confusion, according to this governing body, LTE Advanced and WIMAX Release 2, are the only two formats that should be called true 4G. Long Term Evolution, Super 3G.
via : TechReachClubs.org