Yes, Particle Radius.
I suspect the problem in render is that you are applying Moov on top of HairFromGuides. In your scene Moov is only affecting the Viewport Hair Count, which is different than the render count, so the rest of the hair is not being animated. So solve this increase the viewport hair count to 100%. To avoid this Moov should be always use below HairFromGuides to simulate the guides that will move all the hair independently of the hair amount in viewport and render.
Jeordanis Figuereo (Product Designer. EPHERE Inc.)
