That data is out of date. Go directly to Vanguard's VOO page and you can see that they also hold 507 companies, just like SPY. But it doesn't even matter.
Even if the fund held 510 companies, those last three companies would each represent 0.00% of the fund's holdings. We're literally arguing over a 0.00% difference between two funds.
I also think that the difference between a comparison to total market volume and a comparison to a second competitor is immaterial to this conversation. It doesn't really affect any conclusions about anything.
In conclusion, we're so far off-topic that it may be best to call this thread quits.
Even if the fund held 510 companies, those last three companies would each represent 0.00% of the fund's holdings. We're literally arguing over a 0.00% difference between two funds.
I also think that the difference between a comparison to total market volume and a comparison to a second competitor is immaterial to this conversation. It doesn't really affect any conclusions about anything.
In conclusion, we're so far off-topic that it may be best to call this thread quits.