Posture can be classified into 5 main categories. Unfortunately it's not that simple.
Each category can be further classified into a number of sub groups which go to form your posture type. Everybody falls into a main category and then a combination of sub groups. So although you may have been told you are a certain posture type and been advised to do exercises for that type, they may not be correct for your sub group. A chartered physiotherapist is the expert in assessing your posture and advising accordingly.
Perfect posture is a difficult goal to achieve but the closer you are to perfect the better your body will feel and perform.