Bill Gates suggests the difference:
"You could have the government throw money at the most
politically favored guy in the country to go build a battery
factory. And there are billions of dollars that have been
assigned to that waste. Or you could actually back people
who have better battery ideas."
"But the economics are so, so far from making sense. And
yet that’s where subsidies are going now. We’re putting 90
percent of the subsidies in deployment - this is true in Europe
and the United States - not in R & D. And so unfortunately
you get technologies that, no matter how much of them you
buy, there’s no path to being economical. You need
fundamental breakthroughs, which come more out of basic
The above quotes were lifted from a fairly interesting interview -
here - between Gates and Wired editor-in-chief Chris Anderson
in which Gates expounds on the world's energy crisis.