I don't think that's a fair comparison. VTSAX/VFIAX have accumulated as much difference in
a month as VFWAX and VTIAX have in the
more than two years of data available. I agree there are different indices, but if the indices really focused on different asset classes we'd se a much wider divergence between the funds than we do.
Edit: from the prospectuses: VTIAX invests in the "FTSE Global All Cap ex US Index, a free-float-adjusted market-capitalization-weighted index designed to measure equity market performance
of companies located in developed and emerging markets, excluding the United States", while VFWAX invests in securities to emulate the "FTSE All-World ex US Index, a free-float-adjusted, market-capitalization-weighted index designed to measure equity market performance of international markets". They're both all-cap, developed and emerging.