It's hard to believe sometimes that Mac is never possible to be hacked. Why is that ? Why Windows is very vulnerable to be hacked in? What technologies that brings Macs are truly ahead then the rest ?
I'm not familiar with the specifics but from what I know about software, vulnerabilities in software are related to two things: Bad Design and Bad Implementation (ie bugs).
Mac OS X is written on Darwin which is a Unix Operating System. Unix has been around for many years and was written as enterprise level software. A lot of effort went into making it secure. History has shown that Unix is more secure than windows.
On the other hand, Windows Vista has many of its kernel level operations re-written from XP to be more secure. I'm pretty sure Vista is more secure than XP.
Windows XP is written on Windows NT kernel. I'm not completely familiar with its history but a large reason why XP was exploited so much was because of its prevalence. Hackers don't really bother targeting niche markets because it doesn't bring about as much gains. Targeting XP would mean their exploits would work on over 90% of all PC's in the world. That's a lot of PC's!
The other reason is your average PC user is not completely computer literate. They don't know what a firewall does, or anti-virus. They click random links and download weird files.
Windows XP secured and locked down is actually pretty good. I haven't installed anti-spyware and anti-virus on my XP machines and haven't had a problem.
So in short to answer your questions:
Q: It's hard to believe sometimes that Mac is never possible to be hacked. Why is that ?
A: You're statement isn't true. It is possible to hack Mac's. Just most hackers don't bother because the market is too small.
Q: Why Windows is very vulnerable to be hacked in?
A: Technologically, Windows is based on a less stable operating system than Unix (Windows NT) but more importantly are sociological factors. With 90% market share, hackers want to exploit Windows XP machines. Furthermore many of those people aren't completely computer literate and do not practice safe computing.
Q: What technologies that brings Macs are truly ahead then the rest ?
A: It is based on enterprise level server operating system that is proven to be stable and secure.