[puzzle]

This discussion goes into more detail about commonalities and differences between the two:

https://github.com/census-instrumentation/opencensus-java/is...

The use case of non-request metrics is the biggest difference to me. While it's great to track e.g. resource usage for each incoming request, there are also workloads that don't fit that mold. Think of a garbage collecting background worker: either you use a separate API to push the data or you make up bogus GC RPCs to attach metrics to their traces.

[daenney]

I have to say, after reading through that, I'm still not quite mystified as to what the differences are.