While making a comparative study between turbines and compressors, I noticed some differences between the way they are studied.....pleasehelp me understand why these differences exist.... 1. Efficiency for a turbine = (actual work/ideal work) whereas for compressors, it is (ideal work/actual work). 2. pressure ratio for turbines: (P1/P2) whereas for compressors, it is (P2/P1). 3. We use total to static efficiency in turbines whereas we use static to static efficiency in compressors. 4. Reheating is carried out for turbines whereas preheating is carried out for compressors. 5. Polytropic efficiency of turbine is ((n-1)/n)*(γ/(γ-1)) whereas it is the reciprocal for compressors.