What is the S&P 500? What is the difference with the NY Dow?

$S&P 500 Index (.SPX.US)$ The official name of the S&P 500 is “Standard & Poor's 500 Stock Index (S&P 500 Stock Price Index),” and S&P Dow Jones Index LLC has published it. The purpose is to cover major companies in major industries in the United States, and approximately 500 stocks selected from companies listed on the New York Stock Exchange and NASDAQ taking into account market size, liquidity, industry, etc. are weighted average and indexed by market capitalization. As of the end of April 2022, it covers approximately 87% of the total US stock market value.
Meanwhile, the NY Dow (official name: Dow Jones Industrial Average) is also published by S&P Dow Jones Index LLC, and is characterized by the fact that the number of constituent stocks is very small, with 30 stocks. Also, the difference is that prices are averaged rather than weighted averaging with market capitalization as a calculation method for indices. As of the end of April 2022, it covers approximately 25% of the total US stock market value. $Vanguard Total Stock Market ETF (VTI.US)$ $iShares Core S&P 500 ETF (IVV.US)$