Like Malci mentioned processing is not the same and it is affecting the conversion process. That might not be the only factor that may be causing it so, if any of you want us to personally take a look at your account and give you some feed back feel free to PM me your affiliate user name.
We cannot make a general statement here. So, to find out what is causing you to generate more clicks and no conversions we need to look at your case individually.
Regards,
-Monica-