As I have previously said, there are two main types of Tae kwon-do (TKD) practised in the world: ITF and WTF. The main differences between the two are:
Personally, I don’t see why WTF is an Olympic sport. It gives TKD a bad name and when my friends ask what I do, I specifically say not Olympic TKD. They spend most of their time bouncing on the spot, waiting to use a counter-attack knock-out turning kick. It just seems like a lot of pointless noise and not much action. ITF has a greater variation of techniques, and thus is better to watch.
Something not mentioned in the above table is that WTF predominately focuses on kicks, whereas ITF uses hands as well. I would say ITF is a more traditional Martial Art, whereas WTF has developed into a sport due to its Olympic participation.
However, a good point about WTF is its full-contact nature. I wish ITF did more full-contact and according to TKD Times magazine, a merger between the WTF and ITF will happen in the next few years. As a style, TKD has been taking a beating from other martial arts who have been trying to discredit it as a legitimate form of self defence or fighting. I think unification would help strengthen the style and help fight back against this bad publicity. My other future hopes for TKD, is to see a stronger ITF or kickboxing influence in the Olympics and less politics within the two major organisations.