Both OSes' boot loaders include antimalware detection, and OS X has a password-protected firmware option to prevent startup from external disks; users can't bypass the startup password by booting from a different disk. (One of OS X's handy features is that you can boot a Mac from external disks and network volumes easily, which is great for testing and shared environments.)
Beyond such application security, both OSes support FIPS 140-2 cryptographic encryption. Both OSes also provide IT-manageable on-disk encryption, though Microsoft's BitLocker requires a Trusted Platform Module (TPM) chip to implement it fully, and few PCs have such a chip. For me, that means I can't access corporate email from one of my Windows 8 PCs via the Metro Mail app because it has no TPM to enable encryption, and our Office 2013 Exchange server requires encryption be enabled to gain access. That same server works fine with OS X, iOS, Android, and BlackBerry 10 devices' encryption, and of course it works fine with my TPM-equipped Surface Pro tablet.
Also easier in OS X is data security, thanks to the included Time Machine backup program. With Time Machine, it's dead simple to back up a Mac or OS X Server, and the backups can be encrypted and even rotated among multiple disks. System restoration is also exceedingly easy, with no driver installation or command-line setup involved.
Windows 8 introduced File History, which backs up data files in certain locations to your choice of your startup disk, an external disk, or Microsoft's SkyDrive cloud storage service. Like Time Machine, File History keeps incremental versions of these files so that you can roll back to a previous point in time, but unlike Time Machine, it can't restore your whole PC in case of a crash or simply to transfer your environment to a new machine. Windows 8.1 doesn't change that.
Compatibility: Windows 8.1 vs. OS X Mavericks
Windows 8: 10
OS X Mavericks: 8
Because Windows 8 is Windows 7 with the Metro environment tacked on, it is compatible with all the software, hardware, and services you already have. Yes, some older PCs won't run it, but that's about resource requirements and lack of drivers for those that also don't support Windows 7.
OS X Mavericks of course runs only on Apple's Macs, for which there is a smaller set of hardware and software available than for Windows. Although Apple is ruthless in dropping technologies over time as it deems them problematic or limiting, none have been dropped in Mavericks, which also runs on the same Macs that supported the previous version of the OS (Mountain Lion). The truth is that the everyday hardware people use — mice, keyboards, storage devices, printers, and displays — work on Macs, and the same is true for mainstay software such as Microsoft Office and Intuit QuickBooks, though often (as in these two cases) with inferior versions.
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