A new screen-shots of the new Samsung Ativ S with Windows Mobile build 10070 shows possible changes to the live tiles on the start-screen. The tiles design and layout appear to be very close to each other opposed to previous builds, hence you are likely looking at Windows 10 for Phones.
The screen-shots originates from a Polish website called Windows Mania. This build shows very limited usability and shows an icon for Internet Explorer as well as Project Spartan, which is supposed to become the default browser for Windows 10.
The tiles in the new layout are smaller and closer toe each other, and that does make it look rather crowded if you ask me. Perhaps it is scalable by user preference though. To be 100% sure if this is what we think it is, we'll have to wait until build 10070 will finally become available, the official release from Microsoft that is. You can click on the screenshot (courtesy of Windowsmania.pl) to enlarge it.