A start button included on the taskbar but doesn't open the menu. It'll take users to the start screen when clicked.
There are more settings available to the start screen/modern UI side of the interface.
The Search charm has changed a bit. It now searches the "Everywhere" category by default which also includes Bing, Microsoft's search engine. Though that can be turned off. Instead of full screen, the search pane pops open from the right of the screen. Really handy if one is trying to follow on screen instruction displayed in a web browser or something. Unfortunately, one can no longer search apps. Users will have to open the app first then use the app's built in search function instead.
Apps update automatically now.
Tiles get two new sizes, Large and Small.
and there's a new Help + Tips tile for new users