Yo nice work! it does seem you stylize the heads a bit, I think it works well just note some of the chins are too thin, almost like in anime, and you do tend to make lips narrower than the reference, but construction seems solid and shading is clean, I also like how you leave a line for the malar-labial rhythm and shade behind it. I feel you simplify the shadow areas really well. Your use of angles, curves and straight lines also work very well on the figures
cheers!