The smaller but more mature male is suppressing his development, so there is no telling when he will start to crow as this would immediately bring the dominant male's attention to him which then could start to fight him.
Large fowl cockerels often try to stay under the radar to avoid being...
Looks like a late developing male to me.
As the crowing one is in charge, the bigger one has no responsibilities and can enjoy his junior life.
This would be the reason he does not crow yet. Smaller breeds develop much faster and larger breeds often need several more months to reach maturity.