spyboy vs adware why is this ??

Robo is on the money as usual. You will find that all of these types of programs search for different amounts of spy/ad/trojan ware. While there is overlap in what they each find, you will see that each one can typically find things the others do not. Thus the need to run at least two for the best coverage. Most people use Ad-aware and SpyBot S&D. I also threw in a third. SpySweeper. I use it as a blocker too. It has three shields, memory, cookie, and home page protector.