pick out the main difference between the 2 interpretations (factors, time, events, people involved, short/long term issues etc.)
say what the difference is, quote from the interpretations, and briefly explain how the quotes show the difference
The main difference between Interpretation 1 and Interpretation 2 is that...
To support this, Interpretation 1 says... by mentioning (quote from the source)
However, Interpretation 2 says... by mentioning (quote from the source)
This shows a key difference because...