What is the differance between ITF Taekwondo and WTF Taekwondo?

Hello, I have recently taken an interest to martial arts and have taken up Judo, I would also like to take up and train in another one, one that has striking, with alot of kicking in it. I would like to gain confidence, disipline, fitness and self defence from martial arts, and maybe do a couple of MMA fights one day. I have looked around at different styles of fighting, and have of course found the more popular striking styles, boxing, muay thai etc. They all look very good, especially muay thai or kickboxing, but Taekwondo has really taken my eye. I used to do Taekwondo, I did it for about 6 or 7 months, got my second belt, but left shortly due to getting bored of it, this was about 5 or 6 years ago, and I was only young, but now I wish i had stuck with it. I have looked at videos and found out about WTF Taekwondo and ITF Taekwondo, how are these two styles differant, how is the training differant, how is the sparring differant? What style of Taekwondo would best suit me for my goals? Thank you :)