What Is Difference Between Hacking And Ethical Hacking?

In our daily life we come across words like Hacking And Ethical Hacking.. 
So lets understand difference between them:
Hacking: Its a process of entering inside a system and changing the data in it with out the notice of owner or can be simply stealing the data...
And What Is Ethical Hacking??
Ethical Hacking: It is the hacking done by a certified professional hacker to test the vulnerabilities of a system, ie whether system is vulnerable to any kind of attacks..