Google has changed their homepage.. with add new features and new look.. whereas YouTube also has changed their background and add more services.
Its added link your YouTube account to Google+ and facebook for sharing the video.
Video Review:
It will make it easier to find and follow your favorite channels. And you get more into YouTube.
On the left side of the homepage you can create your own, personal customize on YouTube.
And its create new channel templates.
Whereas Google also add new services like change background image, iGoogle and more..
As before all Google services like You+, Gmail, Images shown at horizontal row, But in new look it shown at Vertical side bar.
Source: Google Blog