Fonseca is a good manager, but not suited for top clubs where you need to be at the top of your leadership skills to deal with primadonas. He's good for those teams who want to reach top 6.
Conceição is much more suited and has the right personality for italian football.
The job he did at Porto with such an average squad is actually impressive.
Of course it also helps that Conceição was a top player in his prime, which helps in getting respect from current top players.
He is a fierce character, he wont take sh*t from anybody and becomes very salty when his teams loses.