What is the difference between CPP and CRP?

[Collang2]

Hello.
While studying OCV(On chip variation), I learned about CPP(Clock Path Pessimism) and CRP(clock reconvergence pessimism).
However, some blogs say that two are the same, and others argue that two are different.
These are same : (http://www.vlsi-expert.com/2011/02/clock-reconvergence-pessimism-crp-basic.html)
CRPR and CPPR should not be confused to be one and the same : (https://www.design-reuse.com/articles/40155/clock-path-pessimism-statistical-vs-logical.html)

When there is a difference in delay in one path by OCV, I think there is CPP(Clock Path Pessimism).

1. Is this right?

2. I want to understand the difference between CPP and CRP.

 

[CambridgeLv]

Considering the foundry manufacture, we introduce the OCV to timing analysis. But the derates were added to every cell in clock path, even from the clock source to last common point. As we know, one specific cell will only perform one actual delay, so these detates are unnecessary pessimism. Hence, we remove this, that's what we call CRPR in Primetime.