Vanguard S&P 500 ETF (NYSEMKT:VOO) are quite similar but also different enough to merit separation. Let's look at when each fund would be a better buy for your portfolio. Vanguard Total Stock: A minimalist's dream Vanguard's Total Stock Market ETF is a preferred holding for someone who values simplicity. If you want to buy a single fund and hold it forever, you really can't go wrong with Vanguard Total Stock. For a paltry 0.03% a year, you'll get effective exposure to all the publicly traded companies in the U.S. stock market, including mid-cap and small-cap companies. Your performance will match the total aggregate performance of the U.S. stock market, assuming you don't trade in and out of the fund.