Pep did make 9 changes to the FA Cup team because he was more interested in finishing off the league title and winning a CL semi-final than winning the FA Cup. They have both done the same thing, I don't see a meaningful difference other than Tuchel openly admits it - and Pep got pretty close when he told everyone the ranking of the competitions this season.
Also I think it's pretty unfair to compare Pep and Tuchel's ability to stand up to their respective bosses. Pep is in a situation where the entire club is begging him to stay as long as possible and their full time mission is to keep him happy. Tuchel has an 18 month contract and arrived 3 months ago.