Difference Btwn Full Install & Upgrade

[MoleSkine]

Hello Macers -

I just got my first new mac the other day. I know that Snow Leopard is coming out. However I am gettign confused by the topic of clean install or upgrade.

What is the difference between the two? Who needs to clean install, who does not? I dont even know what clean install means lol.

If this ? seems childish - sorry -

Help me out - I appreciate it !

 

[celticpride678]

Here are the different install options of Mac OS X: http://support.apple.com/kb/HT1545