The cuckold’s penis stands nearly at attention, his testes tight to his body. His penis appears hopeful and ready.

The bull’s cock hangs down, the suspensory ligament at the top straining under the force of gravity. His balls, large and relaxed, are pulled away from his body by their own weight.

The bull’s cock is better designed to reach the back of a woman’s cervix, spraying hot cum deep inside her, far deeper than the cuckold can. His substantial balls generate more sperm than the cuckold’s. 

Just as the cuckold’s penis looks anxious and excited, the bull’s cock looks relaxed but willing- a reflection of both mens’ character.