Vray CPU & GPU - different engines, same result with PBR workflow?

[AC5L4T3R]

A question that just popped in to my head whilst thinking about a scene I'm going to produce - I know it's often said that you shouldn't switch between CPU and GPU because they're two different render engines, but if all your materials are created in Substance Designer/Painter using PBR workflow, will both engines not produce the same results? I'm not able to test it at the moment, but it would be nice if one of the more knowledgable people could chime in on the subject,

[savage309]

They produce overall the same result, but not pixel to pixel the same (and never will), as long as you stick to the subset of the features of both engines.
It sound strange, but there are different algorithms for bump mapping and lighting for example, that are different, but theoretically still both correct. So it depends on your definition of "the same".

The reason we say that we don't promise the same result between V-Ray and V-Ray GPU is that a) you can use your CPU as CUDA device with V-Ray GPU, and stll utilize all the hardware that you have and b) instead of trying to match the algorithms between V-Ray and V-Ray GPU to be pixel-perfect the same (which is always very hard or impossible, due to the needs of the GPU hardware), we (the V-Ray GPU team) prefer on working on making V-Ray GPU better for our clients in generall.

Let me know if this makes sense or/and if you have any other questions.

Best,
Blago.