Acetylene releases almost 40% of its heat in the inner flame cone. Therefore, acetylene is better for cutting than propane. While temperature wise acetylene is hotter than propane the fact is that people are using propane for cutting incorrectly.
Propane generates less than 10% thermal energy, whereas acetylene generates 40% of thermal energy in the inner flame cone. This helps ensure better weld quality and cutting using oxy acetylene. So, there is far more oxygen being consumed when using propane than acetylene.