The Russell 2000 and S&P 500 have both shown significant price returns since 1978, with the S&P 500 outpacing the Russell 2000, especially in the period after 2010.
The divergence between the two indices has widened in recent years, suggesting that larger-cap stocks (as represented by the S&P 500) have been performing better relative to smaller-cap stocks (as represented by the Russell 2000).