Microsoft advertises their own products and wants you to pay for products in their ecosystem. They will shove the same stuff down your throat (Azure, Onedrive, etc) pretty much whatever you do, which means they don't have a vested interest in behavioral advertising.

Google on the other hand shows ads across the internet, so they have to track you a lot more intimately in order to make you buy a new toaster or whatever (I haven't seen online ads in years, so I don't really know what they're like).