This is a great article about the difference between DFA Funds (my favorites) and standard Index Funds.
Over the past few days, we’ve seen the differences between index funds and passive asset class funds. These differences also provide examples of how passive asset class funds might end up with portfolios whose holdings are significantly different from the universe of initially eligible securities and market-cap weighting. If the screens the fund chooses are based on solid academic evidence and commonsense rules (resulting in a well-structured portfolio), the end result should be superior returns and tracking error to a benchmark that is purely random. (Some years the error will be randomly positive and some years it will be randomly negative, and in the long term it will average close to zero.)