What is the "substantial difference" that might occur between the google shares?
Presumably you're talking about the different share class introduced in the recent stock split, which mean that there are now three Google share classes:
- Class A, ticker symbol GOOGL, one vote per share
- Class B, not traded publically but owned by current and former Google employees, 10 votes per share
- Class C, ticker symbol GOOG, no votes
Due to the voting rights, Class A shares should be worth more than class C, but how much only time will tell. Actually, one could very well argue that a non-voting share of a company that pays no dividends has no value at all. It's unlikely the markets will see it that way, though.