[Matt Mustapick]

What is the difference in tone?
Perhaps there is a very subtle difference, some of the time. But the difference is so subtle that counterexamples to any tone generalizations you might hear about are nearly as common as confirming examples. That said, it may be that a Sitka guitar is more likely to have more warmth and fullness in the midrange, while an Adirondack guitar is more likely to have more separation and more treble projection.

Is either better?
Absolutely not. Adirondack spruce tends to have more fans, and a bit of ooh-la-la, because it generally costs a bit more.

Is there a price difference?
Usually. Adirondack is often more expensive. Price discrepancies across different varieties of woods are determined by supply. The fact that Adirondack costs more (or any other wood that costs more), is often mistakenly associated with some imputed notion of merit.

I think Adirondack and Sitka are both fine choices, so long as the wood is really nice.