what the difference between "Sample test cull rate" and "partical coverage rate"?

I had read more information of Sample test cull rate  from https://community.arm.com/support-forums/f/graphics-gaming-and-vr-forum/47978/what-does-sample-test-cull-rate-mean# and  known the meaning of partical coverage rate from https://developer.arm.com/documentation/102619/0100/Shader-core-unit-overview

seem like, both of them show the rate of a high density of small triangles.  but using stream I got different results for both.  so , could you please tell me about the difference? Thanks a lot