User Account Control (UAC) in Windows 8 is built upon the same technology that helped to secure Windows Vista and Windows 7. There are four levels of control which are outlined under the Windows Support article What are User Account Control Settings? This provides more granular control over the restrictions than was available in Windows Vista. It also works alongside a myriad of additional technologies including Windows Defender, a native full anti malware solution, Secure Boot on compatible systems which protects against malicious boot code, and BitLocker drive encryption in Professional and Enterprise versions to encrypt and protect the integrity of your data.
Windows UAC is a joke. It was something to placate the masses and make them think it would make the OS more secure. Most people get more annoyed with having to click allow all the time for everything the system does and just turn it off. Then MS says you are the one making it less secure when it actually is the OS that isn't secure in the first place.