A Safe Boot performs the following permanent actions: attempting to repair the system volume structure, deleting system KEXT caches, and deleting font caches.
The system version, build number, and hardware serial number are located in the About This Mac dialog or the login screen. The system version number defines the specific version of OS X currently installed. The system build number is an even more specific identifier used primarily by developers. Finally, the hardware serial number is a unique number used to identify your specific Mac.
The OS X Recovery system provides access to Restore System From Time Machine Backup, Install/Reinstall OS X, Get Help Online via Safari, Disk Utility, Startup Disk, Firmware Password Utility, Network Utility, Terminal, and Reset Password.
The local hidden OS X Recovery HD doesn't include the OS X installation assets. So reinstalling OS X Mavericks from here requires high-speed Internet access and the ability to verify access to the installation assets. Upgraded Mac systems are verified by entering the Apple ID used to purchase OS X Mavericks. Verification is automatic for Mac systems that included OS X Mavericks when purchased new.