No the PTO HP and the drawbar HP are diffidently not the same as the Engine HP.
The PTO HP is approx 18 HP on the TO-20. (From Memory)
The engine HP is greatly reduced by friction and gear losses through the transmission.
as a sanity test if they were the same then that 1 cylinder Briggs motor in the lawn tractor could pull and do as much work as the 4 cylinder Continental. -- nope that aint right.