Difference between Google and Apple: Steve Jobs would commit seppuku before spending $5 billion on something he could remake, better, in a couple of months with a handful of dedicated engineers and a barn full of even more dedicated marketeers.
Google would be acquiring a great marketing team by buying GroupOn. We'll see what Apple is going to spend its cash on, but it could be something that Google already has or could replicate easily but Apple can't generate on its own.
For perspective: when I started there, the market cap was less than the amount of cash we had in the bank.