According to Microsoft,
We designed a no-compromise cloud experience where enthusiasts will be able to control files the way they want, while others who are less familiar with the file system can still take advantage of the cloud simply by accessing SkyDrive through the apps they use every day.
With the SkyDrive app, an early version of which will be available at Consumer Preview, we focused on two things: 1) designing a fast, fluid, touch-first version of SkyDrive that makes it quick, easy, and even fun to browse and access your files, and 2) making your SkyDrive available for use from any Metro style app via the file picker (open/save) and the new Share charm in Windows 8.
Also according to Microsoft's blog, SkyDrive app will borrowing features from Dropbox.
iCloud currently offers 5GB of storage space, while SkyDrive is believed to offer 25GB in free storage.
The SkyDrive update is set to launch later this year with support for Windows Vista, Windows 7, and Windows 8 already announced.
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