Since equity mutual funds invest in different sectors, how can an investor make investment decisions based on this factor?
You cannot make investment decisions based on the sectoral exposures taken up by the fund company. Your primary driver to select a fund should be the fund's past performance - how it performed in both the falling and rising markets. Also, look at its long-term track record and the consistency of the fund manager.
The portfolios of most mutual funds look quite similar but that is not the case with their returns or performance. So, while choosing an equity fund, don't look at its portfolio so closely. Rather, choose it based on its long-term performance record.