IVV is an Exchange Traded (closed-end) Fund (ETF). You can purchase it and sell it as you would a regular stock. VFINX is an open-end mutual fund, which you can purchase only once a day at the closing Net Asset Value. Both are intended to mimic ups and downs of the SP 500, so the total return on your investment will be similar. The differences will come mostly from the management fees the management companies (Vanguard and IShares) charge. Those charges are reflected in the price per share so not immediately visible. You can find them in the prospectuses or in research reports by, e.g., www.morningstar.com
As of July 2014, the market cap for iShares MSCI ACWI Index Fund (ACWI) is $5,957,976,000.00.
As of July 2014, the market cap for iShares FTSE China (HK Listed) Index Fund (FCHI) is $30,192,300.00.
As of July 2014, the market cap for iShares MSCI ACWI ex US Index Fund (ACWX) is $1,803,802,000.00.
As of July 2014, the market cap for iShares S&P Emerging Markets Infrastructure Index Fund (EMIF) is $111,660,500.00.
As of July 2014, the market cap for iShares S&P Global Timber &Forestry Index Fund (WOOD) is $307,112,400.00.
The symbol for iShares MSCI ACWI Index Fund in NASDAQ is: ACWI.
The symbol for iShares NASDAQ Biotechnology Index Fund in NASDAQ is: IBB.
The symbol for iShares FTSE China (HK Listed) Index Fund in NASDAQ is: FCHI.
Index funds are investment vehicles that track a particular market index such as the Dow Jones Industrial Average, the Standard & Poor's 500 index and many others. Many firms offer index funds such as Barclays iShares, Vanguard and others. Yahoo Finance also has relevant information about them.
iShares are exchange traded funds or ETF's and they track stock market index. iShares are traded on several stock exchanges globally.
The symbol for iShares Goldman Sachs Semiconductor Index Fund in NASDAQ is: SOXX.
The symbol for iShares S&P Global Nuclear Index Fund in NASDAQ is: NUCL.
The symbol for iShares FTSE EPRA/NAREIT Asia Index Fund in NASDAQ is: IFAS.
The symbol for iShares FTSE EPRA/NAREIT Europe Index Fund in NASDAQ is: IFEU.
The symbol for iShares MSCI ACWI ex US Index Fund in NASDAQ is: ACWX.
The symbol for iShares MSCI Emerging Markets Growth Index Fund in NASDAQ is: EGRW.
The symbol for iShares MSCI Emerging Markets Value Index Fund in NASDAQ is: EVAL.