The long and short of the change is that Google may combine information collected from one service and share it with other Google products. (Gmail, Youtube, Search, Google+, etc.) Google wants to treat you as a single user across all their products.
In Google’s own words:
‘We’re getting rid of over 60 different privacy policies across Google and replacing them with one that’s a lot shorter and easier to read. Our new policy covers multiple products and features, reflecting our desire to create one beautifully simple and intuitive experience across Google.’
You can get an overview and read more information about the new policies and terms of services here: