VTIAX (Total International Index) and VFWAX (FTSE All-World Ex-US Index) are very similar. This includes equity exposure, return, and availability (fund and ETF, investor and admiral shares, expense ratios, etc).
The main difference is that VTIAX has some small-caps, which makes it *slightly* more diversified than VFWAX, which does not have small-caps. This is like the difference between a Total Stock Market Index and an S&P500 Index. Similar returns, but not identical.
VTIAX was originally a fund of funds (European Index, Asian Index, Emerging Market Index), which made it ineligible for the foreign tax credit on dividends. It also didn't have Canada. This made VFWAX a better choice for most people. However, VTIAX changed its index a year or so ago and now includes Canada. Also, it's no longer a fund of funds so is eligible for the foreign tax credit, just like VFWAX. This provides a ~$100 tax credit for every $100K invested. In my opinion, the nod goes to VTIAX because it has small-caps.
I have VFWAX but would change to VTIAX if I could do so with no capital gains taxes. But no big deal either way.