The difference lies in the concentration of equity. The less shareholding, the lower the concentration of shareholding, the smaller the impact of a single stock on the overall fund, and the more you want a big index. . .

The advantage is that the unsystematic risk is smaller, and the overall impact will not be too great because a few stocks are particularly poor.

The disadvantage is that you can't get excess returns, because only a few stocks perform particularly well.

As long as the suggestions are moderate, not too little and not too much. Index funds can't do anything. The number of constituent stocks in the index is generally the number of stocks.