I ordered for an Ubuntu Install CD and obtained a CD by post (Ubuntu 9.10). Is this a Live CD or an Install CD ? What exactly is the definition of a live CD ?
They are now one and the same.
A Live CD allows you to boot the full OS from the CD and try it out fully without affecting your existing HDD OS installation.
It then allows you to install fully to the HDD if required.
Specific info on Ubuntu's Live CDs is available here:
Both are the same. At least, in the case of Ubuntu. When you boot the CD, you can start Ubuntu Linux in LIVE mode. This mode will let you test your hardware for compatibility, for example. Just one thing to remember: since everything is loaded from the CDROM, everything is much slower than it could be expected when booting from a hard disk. However, you will be able to test all your hardware without touching your disk. This lets you have a better look at Linux before making the big move.
I used such CD in the past when shopping for a new laptop. I had the CD with me at the store, asking the salesrep to boot the laptops with the CD, so I can see the compatibility. I then came out of the store with a laptop that was running Ubuntu perfectly, no fuss about drivers, compatibility, wireless, etc. This saved me much time, and avoided me potentially costly errors.
I talk about Ubuntu, but many other distributions offer such live CD's. KNOPPIX is one of them. Some of them will offer an option at boot time, to either start LIVE, or go directly in to the installation process. This second option saves you time, in that it only loads the needed files in memory before starting the setup process, while the LIVE version will need to load a functional environment before letting you start the actual setup process.