Welcome to the TH community, Yeni_09!
Well, what is better really depends on the purpose you intend to use the HDD for.
IntelliPower RPM is a fine-tuned balance of spin speed, transfer rate, and caching algorithms designed to deliver both significant power savings and provide solid performance. Additionally they consume less power and that's why the are Green. Here's an article from our knowledge base that explains the difference between the IntelliPower Green drives and the traditional 7,200 RPM drives:
http://products.wdc.com/support/kb.ashx?id=Szt6f2
Keep me posted if you have more questions about them!
SuperSoph_WD