SPY), but the gap between the iShares S&P Small Cap 600 Growth ( IJT) and Value ( IJS) is about 3%, for example. A big reason for the difference between growth and value is sector allocation. Small cap financials have done well this year, with mutual fund FBR Small Cap Financials ( FBRSX) up more than 20% in 2010; value tends to have larger financial allocations. The performance gap between small-cap growth ETFs, however, is much narrower. Year to date, the gap between iShares Morningstar Small Cap Growth ( JKK) and Vanguard Small Cap Growth ( VBK) is less than 3%. The funds tend to have similar portfolios, and the ones with the largest deviation from the group have been underperforming this year. Therefore, it requires digging a bit deeper to see which ETFs are the best in the pack. A comparison of volume shows that three funds attract most of the trades : iShares Small Cap 600 Growth ( IJT), iShares Russell 2000 Growth ( IWO) and Vanguard Small Cap Growth ( VBK). Of the three, IWO dominates with more than five times the volume of the other two funds combined. Traders will definitely find IWO the better choice. IWO holds 1,276 stocks, more than triple the holdings in IJT and ahead of VBK's 1,000 holdings. In terms of sector allocations, the three funds are very similar. There are few major differences that stand out. One is the 24% heath care exposure in IWO, which is more than the 18% in the other two ETFs. Where IJT is underweight health care (relative to IWO), it is overweight financials, with exposure nearly double the other two funds, at 14% of assets. VBK, meanwhile, takes a balanced approach, with technology and industrial exposure about 3% higher than the other funds, at 26% and 15%, respectively. This balanced approach makes VBK a better choice for long-term, buy-and-hold investors because the fund is less likely to fluctuate from sector exposure.