You can use this simple calculator to estimate the impact of differing annual fees on a pension balance over a typical saving term.
The calculated (estimated) value of the two pensions are,
This calculator assumes an annual growth of 5% over a term of 30 years with both growth and fees are applied monthly. This means it gives a good illustration of the fee difference over a typical pension term.
If there are fixed initial fees simply remove the fee from the initial value. Likewise for fixed annual fees simply remove the fee from the monthly contribution.