Question: What is the difference between adware and spyware?
Answer: Adware collects information about your computer usage in order to send targeted ads. As long as you are prepared to put up with a few ads being displayed this may not be of major concern and it may be the price that you have to pay in order to be able to use particular software without having to pay for it with money. This doesn't mean that all programs that display ads are classified as adware as only those that collect information from you and use it to determine which ads to display (eg. Google) are actually adware. To protect yourself against adware all you need to do is to delete the tracking cookie that the adware uses to identify you in its tracking info.
Spyware collects information from your computer for other purposes (eg. so they can buy things using your credit card or use your computer to launch an attack against a US Military web site). This sort of behaviour is far more harmful and so it is far more important to stop the tracking cookie from ever being set with this type of security threat.
This article written by Stephen Chapman, Felgall Pty Ltd.