Yes there are different types of doctors. When you study medicine, you would have to take a pre-medical course first for roughly around 4 years then after that you can choose your specialization. This is the 2nd phase. This is the next step for you to decide what type of doctor would you want to be - do you want to be a surgeon, pediatrician looking after kids, OB GYN helping women give birth to beautiful babies, etc. The specialization will take another few years or so, Then of course, you have to take your board exam to be a fully pledged doctor.
They say that when you pursue medicine, it will take you at least 8-10 years to complete the process but hey this is a very good investment. Being in the medical field takes a lot of determination, hard work and effort but if your heart is into it, I am confident that you will be a good one when you pursue your dreams. Good luck! I am sure you will make the best decision!