RSP holds all 500 S&P 500 constituents at equal weight rather than by market cap, in contrast to VOO/SPY's heavy concentration in megacap tech names like Nvidia and Apple.

Its 16.2% one-year return has trailed VOO's 19.0%, since megacap tech has significantly outperformed the broader market in recent years. It suits investors who want to reduce megacap concentration risk, but note its 0.20% expense ratio is much higher than VOO's 0.03%.