Numbers are different for getc and getv commands. As far as I released that getc reads data at the centre of the cell assuming the entire cell has the same value. getv uses interpolation to get values at verticies.

The question is which one is accurate or to be used?

Thanks for any explanation.

The cell centroidal values are the actual ones computed by the STAR solver. The vertex values are interpolated by prostar from the centroidal values during post-processing, mostly to produce smooth contour plots. In an absolute sense, you could say the centroidal values are more accurate, but if your mesh is fine enough, there should not be any real significant differences. Mostly it depends on what you want your plots to look like.