IJH tracks the S&P MidCap 400 index, providing mid-cap exposure similar to VO. Its top holdings — Twilio, Illumina, and others — differ somewhat from VO's composition.

Its 14.8% one-year return is roughly comparable to VO's 13.7%. Choosing between VO (Vanguard) and IJH (iShares/S&P) usually comes down more to your broker's fee structure than to meaningful differences in index methodology.