3G vs. 4G: What’s the Difference?: Good summary on the unholy, craptastic mess that is naming standards for mobile broadband. Basically, terms like “3G” and “4G” mean very little.
4G phones are supposed to be even faster, but that’s not always the case. There are so many technologies called “4G,” and so many ways to implement them, that the term is almost meaningless. The International Telecommunications Union, a standards body, tried to issue requirements to call a network 4G but they were ignored by carriers, and eventually the ITU backed down.[…]
There’s one rule to follow: Each generation will offer faster Internet speeds than the last, that is, on the same carrier. Sprint’s WiMAX 4G is almost always faster than its CDMA 3G. But AT&T’s 3G HSPA can be faster than MetroPCS’s 4G LTE. You can rely on speeds to move up within your carrier, though.