Think of the slug as hitting your target over the head with a brick and the deep penetrating bullet as stabbing him.
Well having killed large deer with both Imust say the damage caused was greater with the slugs. I used a 150 gr 30-06 and of course my winchester 1300 with the rifled barrel. I have also shot deer with a smoothbore (earl years), most went completly thru the deer as did the 30-06 but having a larger face the slug did a lot more damage to the deer. Dont use kinetic energy stuff or scientific explaintions, just my life exp.
I shot a wheel rim with both the slug tore a hole in it the 06? not so much...