The 2 images below show the effect of changing the stepover on quality.
The first image shows a design 10" wide, cut with a 60 degree V cutter and small stepover = high resolution and good quality
The estimate machining time is approx 12 minutes.
The second image is the same design and cutter settings, but using a larger stepover, hence lower quality and will take approx 6 minutes to cut.
Cutting the same job using an 1/8th Ball nose cutter to get the 'Embossed look' would take around 2 hours to machine.
Hope this helps with the difference between the grayscale emboss approach and how PhotoVCarve works.
Tony