Respiratory HELP

I think that it will mainly be differentiating between different types of diseases and resp. conditions.(upper and lower resp. tract, conditions with the nose and sinuses, pneumonia, pulmonary edema/embolism.....etc.) I just haven't been doing very well on our last tests and I really need to do well........I'm studying very hard, I just thought someone may have some pointers on differentiating things....thank you!