We don't have an. reliable benchmarks at the moment, but at least according to Geekbench 5 results the 2.4 CPU has a healthy lead over the 2.3 one (around 10% in multi-core scores). I have also seen some screenshots of a person benchmarking the laptop, and the CPU seems to be able to sustain around 60 watts of continuous power draw, which is a big difference over the 15" model (that one could only do 45-50W).
As to the GPU, I am not sure why you think that chassis will impact the difference between 4GB and 8GB VRAM. Both 4GB and 8GB GPU versions have identical performance, it's just that one of them has more VRAM and would need to swap less if your application requires large amounts of data to be on the GPU