(spoiler) I spotted the differences so you dont have to because "Aint nobody got time for that."
1-10 is the same image with the dick moving deeper and then out (might be well animated if you string them together. Probably not.) 11-19 is the same image in varios levels of undress, and hairiness levels 20-26 is states of hairiness and undress zoomed out and slightly lower rez. Cheers