What is the need for phishing threshold when then is a already a term called PCL(Phishing Confidence level)?

Question

Here are reference to what I'm talking about. (https://i.stack.imgur.com/6MhPR.png)(https://i.stack.imgur.com/B9lbj.png) (https://i.stack.imgur.com/4eoni.png)

I need a clear explanation for the need of Phishing threshold ,when there already Phishing Confidence Level (PCL) is available for filtering level configuration.

We can see that in anti spam policies creation there is only SCL involved in the filtering process. This is the major root cause for my Query.