Expense differences, volatility, and risk profiles set these metal ETFs apart for investors weighing cost against performance history.The iShares Gold Trust (IAU +0.11%) and iShares Silver Trust (SLV +3.58%) both offer direct exposure to precious metals, but differ in historical risk, recent returns, and ongoing costs.Both funds are designed as convenient vehicles for investors seeking to track the price of either gold or silver, rather than owning the physical commodities directly. Comparing IAU and SLV co ...