PTX - what is a CTA?

Question

I'm studying PTX and I don't understand how a CTA (compute thread array) is different from a CUDA block.

Are they the same thing? It seems to me that for now (I'm just at the beginning of the PTX document) they're just the same

Answer 1

Yes, the PTX cooperative thread array is conceptually and functionally the same as a block in CUDA or a workgroup in OpenCL.

Answer 2

The Thread Hierarchy section of the CUDA PTX ISA document explains that, essentially, CTA means a CUDA block.

Also note that it's actually not a "Compute Thread Array", but rather a "Cooperative Thread Array" (!).